Use of ondansetron during pregnancy and the risk of major congenital malformations: A systematic review and meta-analysis

Accepted Manuscript Title: Use of Ondansetron during Pregnancy and the Risk of Major Congenital Malformations: A Systematic Review and Meta-analysis Authors: Yusuf Cem Kaplan, Jonathan Luke Richardson, Elif Keskin-Arslan, Hilal Erol-Coskun, Debra Kennedy PII: DOI: Reference:

S0890-6238(18)30529-X https://doi.org/10.1016/j.reprotox.2019.03.001 RTX 7797

To appear in:

Reproductive Toxicology

Received date: Revised date: Accepted date:

17 September 2018 27 February 2019 4 March 2019

Please cite this article as: Kaplan YC, Richardson JL, Keskin-Arslan E, Erol-Coskun H, Kennedy D, Use of Ondansetron during Pregnancy and the Risk of Major Congenital Malformations: A Systematic Review and Meta-analysis, Reproductive Toxicology (2019), https://doi.org/10.1016/j.reprotox.2019.03.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Use of Ondansetron during Pregnancy and the Risk of Major Congenital Malformations: A Systematic Review and Meta-analysis Yusuf Cem Kaplan1,2 , Jonathan Luke Richardson3, Elif Keskin-Arslan1,2, Hilal Erol-Coskun1,2, Debra Kennedy4,5. Author initials: Y C Kaplan, J L Richardson, E Keskin-Arslan, H Erol-Coskun, D Kennedy.

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Author affiliations 1. Terafar - Izmir Katip Celebi University Teratology Information, Training and Research Center, Izmir, Turkey.

2. Izmir Katip Celebi University School of Medicine, Department of Pharmacology Izmir, Turkey

3. The UK Teratology Information Service, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.

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4. Mothersafe, The Royal Hospital for Women, Sydney, New South Wales, Australia.

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5 School of women’s and Children’s Health University of New South Wales Australia

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Running Title: Ondansetron and Congenital Malformations

birth defects; hyperemesis gravidarum

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Keywords: Ondansetron; pregnancy; nausea and vomiting of pregnancy; congenital abnormalities;

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Word Count: 3572 (not including abstract, tables, figures, acknowledgements or references)

Figures: 4

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Tables: 2

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Corresponding Author: Yusuf Cem Kaplan, M.D.

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Director, Terafar, Izmir Katip Celebi University Teratology Information, Training and Research Center, Izmir, Turkey

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Address: Izmir Katip Celebi Ataturk Egitim ve Arastirma Hastanesi, Klinik Farmakoloji ve Toksikoloji Birimi, 35360, Karabaglar, Izmir, TURKEY. Telephone: +902322444444 Ext.1798 Fax: +90 232 245 04 38 Email: [email protected]

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Research Highlights  The primary aim of this study was to investigate major congenital malformation risks following ondansetron use in pregnancy.

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Our primary analysis suggested no significant increase in risk of overall major or specific malformations following ondansetron use in pregnancy. However, further surveillance of genitourinary malformations may be justified.

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Our secondary objectives were to analyse rates of subgroup malformations such as heart defects, orofacial clefts and isolated cleft palate, genitourinary malformations and hypospadias. Pooled data from studies comparing ondansetron-exposed and healthy control pregnancies did not describe statistically significant increased risks for overall major malformations, heart defects, orofacial clefts, genitourinary malformations or hypospadias. However, pooled data from studies comparing ondansetron-exposed and diseasematched control pregnancies identified raised point estimates for genitourinary malformations and hypospadias risks.

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

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Introduction

Nausea and vomiting of pregnancy (NVP) affects about 70% of all women during their pregnancy (1,

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2). Symptoms usually start early in the first trimester (4-6 weeks), peak between 8-12 weeks and end by the 16th week of pregnancy in the majority of women (3, 4). NVP has the potential to

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adversely affect the patient’s quality of life, social functioning and occupational performance (5, 6). The most severe form, hyperemesis gravidarum (HG), may affect up to 2% of pregnant women by

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leading to significant weight loss, dehydration and electrolyte imbalance necessitating hospitalization (3). Refractory NVP may even lead to pregnant women considering termination of an

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otherwise wanted pregnancy (6).

Ondansetron is a serotonin 5-HT3 receptor antagonist, a pharmacological class which was originally

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developed to control chemotherapy-induced emesis (7). Current NVP treatment guidelines suggest that its use may be considered if first-line drugs such as Vitamin B6 (pyridoxine), doxylamine/Vitamin B6, diphenydramine, dimenhydrinate, meclizine, metoclopramide and their

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combinations have failed to suppress maternal symptoms (4, 8 ). However, studies investigating the safety of maternal ondansetron use during pregnancy have reported inconsistent findings. Although the major congenital malformation rate was not suggested to be increased in any of the particular studies to date (9-15), two prospective cohort studies have reported an increase in risk of heart defects (12, 13) while one case-control study identified a significant increase in the risk of isolated cleft palate,(16) and another reporting conflicting findings for this outcome in two different datasets(17). Page 2

Given that NVP is the most common medical condition during pregnancy which overlaps with the period of organogenesis and that ondansetron’s off-label prescription rate to pregnant women has been on the rise (10, 13, 18), it is important to investigate the safety of ondansetron use during pregnancy. Our objective while undertaking this first meta-analysis of the controlled epidemiological studies to date, was to assess whether ondansetron use in pregnancy is associated with an increase

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in the rate of major congenital malformations. Our secondary objective was to analyze the rates of subgroup of malformations such as heart defects, orofacial clefts and isolated cleft palate, genitourinary malformations and hypospadias. 2. Methods 2.1 Search Strategy

Searches were conducted by the study authors in PubMed/MEDLINE, Cochrane Central Register of Controlled Trials

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and Reprotox databases from inception to 21st September 2016 using the following search terms and their combinations with BOOLEAN operators by the study authors: ondansetron, pregnancy, congenital malformations,

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congenital abnormalities, birth defects, cardiovascular malformations and heart defects. We applied no language or

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date restrictions. A manual search has also been held through the reference list of the previous systematic reviews in order to identify other potentially eligible studies. The study identification and inclusion flow chart was prepared in

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compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (19) and is presented in Figure 1. Our findings are reported in adherence with the Meta-Analysis of Observational Studies in

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Epidemiology (MOOSE) guidelines (20).

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2.2 Inclusion and exclusion criteria

Observational cohort and case-control studies investigating major congenital malformations after maternal use of

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ondansetron in pregnancy were included in this meta-analysis. A study was considered eligible if it met the following criteria: (1) Exposure to ondansetron during pregnancy was reported; (2) A healthy or disease-matched control (either nausea and vomiting of pregnancy or hyperemesis gravidarum) group was included. These control groups

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should be unexposed to ondansetron but they might be exposed to either non-teratogenic drugs or antiemetics other than ondansetron; (3) Either the total number of exposure and outcome events or point estimates were reported; (4) The data reported were not overlapping with another study. If an overlap between two studies was detected, we

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preferred to include the one that received higher score regarding methodological quality. However, a sensitivity analysis including each of the overlapping studies at a time was also conducted. The exclusion criteria were case reports and series, animal studies, editorials and reviews. 2.3 Quality assessment

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The Newcastle-Ottawa scale (21) was used for quality assessment of the study methodologies. The authors were not blinded to the author names, institutions, results or journals of the publications. Any disagreements were resolved through subsequent discussion with another author (Y.C.K.). 2.4 Outcome measures The main outcome of interest for this meta-analysis was overall major congenital malformations. The secondary

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outcomes of interest were heart defects, orofacial clefts, isolated cleft palate, genitourinary malformations and hypospadias. 2.5 Data extraction

Two authors (E.K-A. and H.E-C.) independently reviewed the studies. The data were extracted by using a standardized data extraction form and presented in Table 1. We communicated through e-mail with Colvin et al., (10) and Fejzo et al., (14) regarding the details of the malformations in their studies. We also communicated with Danielsson et al.

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through a correspondence about an inconsistency in the reported point estimate and confidence limits regarding heart defects in their study (13). First trimester exposures, if available, were considered. Any disagreements were

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discussed and resolved by consulting with another author (Y.C.K.). The authors were not blinded to the details of the

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2.6 Classification of malformations

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publications.

Most of the studies had already classified the malformations they investigated, therefore relevant point

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estimates or event numbers were used to pool the data. The malformations which were retrieved by personal communication through e-mail with Colvin et al., (10) Fejzo et al. (14) were classified independently by the

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study authors (Y.C.K., J.L.R., E.K-A. and H.E-C.) and consensus was achieved through discussion with another author (D.K.). Because the malformations were classified using the Malformation Coding Guides of European

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Surveillance of Congenital Anomalies (EUROCAT) (22, 23), as major and minor, JRC-EUROCAT Central Registry was also consulted through e-mail in case of any disagreements among the authors regarding the classification. The authors were not blinded regarding whether the malformations belonged to exposed or

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control groups during the classification of malformations. 2.7 Meta-analytic methods

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For pooling the events, data were extracted from eligible studies and arranged in a 2 by 2 table. The odds ratios (OR) and 95% confidence intervals (CI) for the dichotomous outcomes of interest were calculated using Mantel-Haenszel method and outcome data was combined by using a random-effects model with RevMan 5.3 (Review Manager 5.3; Cochrane Collaboration, Oxford, UK). For pooling the point estimates, we extracted ORs (or aORs where available from eligible studies). For the study by Einarson et al., (9) Colvin et al. (10) and Fejzo et al. (14) we calculated the ORs for the outcomes of interest from the data accordingly. The log odds ratios (log [OR]) and standard errors (SE) were combined using generic inverse variance method and random-effects model in RevMan 5.3 (Review Manager 5.3; Page 4

Cochrane Collaboration, Oxford, UK) (24). Heterogeneity was assessed utilizing the Q and I-square statistic. An Isquare value between 25%-50% signified low heterogeneity, between 50%- 75% moderate and >75% signified high heterogeneity (25). A funnel plot was not utilized to assess publication bias since it is suggested to have low power for detecting asymmetry with good accuracy if the number of included studies is below ten (26), which was the case with our meta-analysis.

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Results

The study identification and inclusion flow chart was prepared in compliance PRISMA guidelines

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(19) and is presented in Figure 1 below.

Figure 1. PRISMA flow diagram Seven cohort studies (9-15) and two case-control studies (16, 17) were identified as eligible for this meta-analysis; (details presented in Table 1). Four of the cohort studies (11-13, 15) originated from Scandinavian registries (two from Denmark and two from Sweden) while two were from North Page 5

America (Canada and the U.S. ) (9, 14) and one was undertaken in Australia (10). Because the two Danish studies, Pasternak et al.,(11) and Andersen et al., (12) investigated largely overlapping data and yielded conflicting results, we undertook a sensitivity analysis and presented two different forest plots for the outcomes of interest by including each Danish study one at a time. Of importance, the study by Andersen et al. (12) was published as an abstract which provided very limited details that led to a relatively lower methodological quality score (Table 1), and as such, the study by Pasternak

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et al.(11) was included in the primary analysis. The study by Asker et al. was also excluded since it did not report the details of the control group and had overlapping data (Swedish Medical Birth

Register) with the study by Danielsson et al., which was much more recent (1995-2002 vs 1995-

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2012, respectively).

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Table 1. Characteristics of the studies.

Table 1a. Cohort studies investigating major and organ-specific congenital malformation rates following ondansetron exposure during pregnancy Andersen et al. 2013

Canada and Australia Prospective Cohort

Australia

Denmark

2002-2005 Registry-based Cohort

Nausea and Vomiting of Pregnancy Helpline or Teratogen Information Services (TIS) at The Motherisk Program in Toronto or The Mothersafe Program in Sydney

Fejzo et al. 2016

Denmark

Danielsson et al. 2014 Sweden

2004-2011 Registry-based Cohort

1997-2010 Registry-based Cohort

1998–2012 Registry-based Cohort

2007-2014 Retrospective Cohort

Australian Pharmaceutical Benefits Scheme, Western Australian Data Linkage System, Hospital Morbidity Data System, Midwives’ Notification System, Registry of Births and Deaths, Western Australian Register of Developmental Anomalies (WARDA)

Danish Medical Birth Registry, Danish National Patient Register, Danish National Prescription Registry, Danish Central Person Register, Statistics Denmark

Danish Medical Birth Registry, National Hospital Register, Danish National Prescription Registry

Swedish Medical Birth Register, Swedish Prescription Register, Birth Defect Register, Midwife Interview

Hyperemesis Education and Research Founda-tion Web site (www.HelpHer.org)

96,698 pregnant women / 98,325 infants

608,385 pregnancies / 442,748 infants

897,018 births

1,501,434 infants

1335 pregnant women / 3396 pregnancies /2679 live birts

United States

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Data source

Pasternak et al. 2013

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Study Period Design/setting

Colvin et al. 2013

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Country

Einarson et al. 2004

Number of participants

528 pregnant women / 491 infants

Number of events

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N U SC RI PT Total: 1233 MCM: 36 Heart defects: 13 Oral cleft: 3 Genitourinary: 8 Renal defects: 4 Hypospadias: 4

Total: 1234 CM: 58 Heart defects: N/A Oral cleft: N/A Genitourinary: N/A Renal defects: N/A Hypospadias: N/A

Total: 1349 MCM: 38 Heart defects: 19 Oral cleft: 1 Genitourinary: 4 Renal defects: 0 Hypospadias: 3

Total: 952 MCM: 15 Heart defects: 5 Oral cleft: 1 Genitourinary: 2 Renal defects: 0 Hypospadias: 2

Total birth: 162 MCM: 3 Heart defects: 2 Oral cleft: 0 Genitourinary: 1 Renal defects: 0 Hypospadias: 1

Total: 98,062 MCM: 3975 Heart defects: 641 Oral cleft: 215 Genitourinary: 1352 Renal defects: N/A Hypospadias: 361

Total: 4932 MCM: 141 Heart defects: 50 Oral cleft: 13 Genitourinary: 25 Renal defects: 11 Hypospadias: 12

Total: 895,914 CM: 31357 Heart defects: N/A Oral cleft: N/A Genitourinary: N/A Renal defects: N/A Hypospadias: N/A

Total: 1,458,697 MCM: 42,392 Heart defects: 14,412 Oral cleft: N/A Genitourinary: N/A Renal defects: N/A Hypospadias: N/A

Total: 1286 MCM: 16 Heart defects: 9 Oral cleft: 2 Genitourinary: 2 Renal defects: 1 Hypospadias: 1

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Total: 211 MCM: 10 Heart defects: a Oral cleft: a Genitourinary: 5 Renal defects: N/A Hypospadias: a

Total birth: 160 MCM: 3 Heart defects: 1 Oral cleft: 0 Genitourinary: 1 Renal defects: 1 Hypospadias: 0

Total: 441 MCM: 7 Heart defects: 1 Oral cleft: 0 Genitourinary: 1 Renal defects: 1 Hypospadias: 0

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NVP/HG control:

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Unexposed:

Total birth: 169 MCM: 6 Heart defects: 1 Oral cleft: 0 Genitourinary: 4 Renal defects: 1 Hypospadias: 3

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Ondansetronexposed (First trimester):

Inclusion criteria

-All women with ondansetron exposure who were less than three months pregnant at the time of calling to the TIS within a two year period

-All births in Western Australian between 2002-2005

-All singleton live birth or stillbirth or ended with any abortive outcome in Denmark between January 1, 2004 - March 31, 2011

-All women giving birth in Denmark between 1997 and 2010

-All live births in Sweden between 1998 and 2012 - Events with relatively severe congenital malformation

- All women with a diagnosis of HG who recruited to website between 2007 and 2014 - Singleton pregnancy - Treatment with IV fluids and/or total

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N/A

- Minor defects with no disfiguring or requirement of treatment

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Exclusion criteria

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- Less than five subjects in each defects subgroup were not mentioned

Exposure

Ondansetron, Other antiemetics; diclectin, metoclopramide, phenothiazines and ginger

Ondansetron

-Pregnancies with missing or implausible gestational age or birth weight (for birth weight analysis) - Multiple records on overlapping dates - The abortions which were occurred prior than 6th gestational weeks - Ondansetron prescriptions within 1 month before pregnancy onset -Infants with chromosomal aberrations (e.g., Down’s syndrome) and those with known causes of birth defects (e.g., fetal alcohol syndrome) -Unpaired infants after propensity score analysis Ondansetron

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Ondansetron, metoclopramide

parenteral nutrition/nasogastric feeding tube - Relatively common and clinically less significant malformations with a variable registration such us preauricular tags, tonguetie, patent ductus in preterm infants, single umbilical artery,undescended testis, hip (sub)luxation, and nevus - Duplications in the prescription register and midwife interviews

-Under 18 years - Living outside the United States

Ondansetron, meclozine

Ondansetron, metoclopramide, promethazine

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Exposure to ondansetron during first trimester

First trimester dispensing were included the analysis of major birth defect. -Ondansetron dispensing at any time during pregnancy for other outcomes (stillbirth, birth weight etc.)

Controls were enrolled in the same way with exposed group.

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Control

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Ondansetron exposures reported at the first prenatal visit

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Exposure time window

Women with no ondansetron dispensing in the same period with exposed group

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Group 2 with NVP who were not exposed to ondansetron, they had used other antiemetics

Method of congenital malformation diagnosis

Group 3 who were exposed ton onteratogen drugs or had not used any medication Standardised interview with mothers and then for verification of baby’s health were asked their physicians

Ondansetron dispensing to the women in first day of the last menstrual period through 12 gestational weeks for any major birth defect. -Ondansetron dispensing at any time during pregnancy for other outcomes (preterm birth, birth weight, stillbirth and spontaneous abortus)

Women redeemed ondansetron prescriptions during first trimester

Women with no ondansetron dispensing in the same period with exposed group, 1 exposed infant matched with 4 unexposed infants

Women with no ondansetron prescriptions

Exposure to ondansetron after last menstruel period through 12 gestational weeks or ondansetron prescribed during first trimester

Exposure to ondansetron any time during pregnancy.

Women with no exposure to ondansetron and meclizine during first trimester

HG controls: Women who suffered from HG and not exposure ondansetron or exposed to other treatments for NVP and also had minimum 2 follow-up after 27 weeks.

For our analysis only first trimester exposures were extracted from unpublished data.

Healthy controls: Women with known history of normal nausea/vomiting or no nausea/vomiting at least in 2 pregnancies. WARDA classification and 5-digit British Paediatric Association International Classification of Diseases, Ninth

European Surveillance of Congenital Anomalies (EUROCAT) classification, International

EUROCAT classification

International Classification of Diseases code

Structured online surveys were done by mothers

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Revision (ICD-9) system

Use of ondansetron any time during pregnancy

Classification of Diseases; the tenth revision (ICD-10) Age, place of birth, county of residence, married or living with partner, level of education, income, pregnancy history, smoking, prepregnancy BMI, medical history, health care utilization, use of other antiemetics (metoclopramide, antiemetic antihistamines, scopalamine, and domperidone) Use of ondansetron during first trimester

Age, smoking, alcohol status and gestational age at time of call

Maternal age, previous preterm birth, smoking during pregnancy, socioeconomic situation, parity, private health insurance, and multiple birth, caesarean delivery (The adjustment were done only for preterm birth, elective caesarean and postpartum haemorrhagia)

Any birth defect: OR: 1.3 (0.8–2.1)

MCM: aOR: 1.12 (0.69-1.82)

Results relevant to this meta-analysis

Use of ondansetron during first trimester

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OR/RR (95%CI) or p value

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Covariates for adjustment

with letter

MCM: 6/169 vs 6/322 (p=0.52) Hypospadias: 3/169 vs 1/322 (p=0.25)

MCM: OR: 1.1 (0.6–2.0) Use of ondansetron during first trimester

Adjustment was reported but authors did not mention which covariates were included.

Year of birth, maternal age, parity, smoking in early pregnancy, and body mass index

Ethnicity, education, termination, miscarriage, age

Use of ondansetron during first trimester

Use of ondansetron during first trimester

Use of ondansetron any time during pregnancy

MCM: aOR: 1.3 (1.0-1.7)

Any malformation: OR: 0.95 (0.72–1.26)

Birth defects

Heart defect: aOR: 2.0 (1.3-3.1)

MCM: OR: 1.11 (0.81–1.53)

HG/Ondansetron group vs HG/No Ondansetron group

Heart defect: OR: 1.62 (1.04–2.54)

3.47% vs 3.40% (p=1.0)

MCM: OR: 1.2 (0.6–2.2) Obstructive defects of

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renal pelvis and ureter: OR: 6.2 (2.0-19.5) Quality assessment (Newcastle-Ottawa scale)

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Abbreviations are as follows: Not available (N/A), not reported (NR), congenital malformation (CM), major congenital malformation (MCM), nausea and vomiting during pregnancy (NVP), hyperemesis gravidarum (HG). a Authors’s institution does not allow to publish sample sizes less than 5.

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Table 1b. Case-control studies investigating the association between organ-specific malformations and ondansetron exposure during pregnancy

United States 2005-2009 1997–2013 Population-based Casecontrol Study

Multi-site Population-based Casecontrol Study

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United States 1997-2004

Exposure

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Design/Setting

Van Bennekom et al. 2016

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Country Study Period

Anderka et al. 2012

National Birth Defects Prevention Study (NBDPS)

National Birth Defects Prevention Study (NBDPS) (2005-2009) Slone Birth Defects Study (BDS) (1997–2013)

Number of participants

22,381 pregnant women

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Data source

Case Control

4524 5859

Exposure time window

Control

Anderka et al. 2012

Van Bennekom et al. 2016

Ondansetron Other Antiemetics; promethazine, diphenhydramine, cetirizine, doxylamine plus pyridoxine, cetirizine, phenothiazines, prochlorperazine, metoclopramide, antacids, H2 blockers, proton pump inhibitors, pyridoxine, steroids, emetrol/coke syrup, herbal/natural products, ginger First trimester use of ondansetron

Ondansetron

Control subjects without birth defects were randomly selected. Hypospadias analysis done with only male controls.

First trimester use of ondansetron

N/A

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Number of ondansetron exposures in case vs control group OR/RR (95% CI)

Cleft lip with or without palate 7/933 vs 44/4,009 aOR: 0.88 (0.38–2.00)

Cleft palate NBDPS aOR: 1.5 (0.9-2.5) BDS aOR: 0.4 (0.2-0.8)

Cleft palate 11/525 vs 44/4009 aOR: 2.37 (1.18–4.76)

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-Infants whose follow-up interviews were available and expected dates of delivery were between September 24, 1997 and December 31, 2004. -All infants who reside in the study areas - Anencephaly, craniorachischisis, spina bifida, or encephalocele were included for NTDs - Only infants with severe hypospadias

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Inclusion criteria

N/A

Covariates for adjustment

Maternal age, race/ethnicity and education, parity, plurality, previous miscarriage, any smoking in the month before conception through the first trimester, body mass index, infant sex, any folic acid use in the month before conception through the first trimester, use of unknown antiemetic, site, and expected year of delivery

Adjustment was reported but authors did not mentioned which covariates were included.

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Renal agenesis/dysplasia BDS aOR: 2.3 (1.3-4.0)

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Hypospadias 5/655 vs 18/1956 aOR: 0.57 (0.20–1.60)

Maternal interviews in the birth defects surveillance systems Clinical geneticists reviewed information of cases from medical and confirmed the cases

Hypoplastic left heart syndrome NBDPS aOR: 1.5 (0.7-3.1)

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Neural tube defects (NTDs) 4/711 vs 44/4,016 aOR: 0.60 (0.21–1.68)

Method of congenital malformation diagnosis

Diaphragmatic hernia NBDPS aOR: 1.7 (0.9-3.5) N/A

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-Cases with recognized or strongly suspected chromosome abnormalities or single-gene conditions -Infants with clefts secondary to another defect (e.g., holoprosencephaly or amniotic band sequence) -Unconfirmed orofacial clefts after birth -First-degree hypospadias (urethral opening on the glans or corona) -For evaluation family history, cases with same birth defects with a parent, sibling or half sibling were excluded - Women with pre-existing diabetes and infants with more than one major birth defect

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Exclusion criteria

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Abbreviations are as follows: Not available (N/A), not reported (NR), congenital malformation (CM), major congenital malformation (MCM).

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The studies by Pasternak et al.(11) and Andersen et al.(12) and the Australian study by Colvin et al. (10) used relevant birth and electronic registries for the data, while the Canadian study, by Einarson et al. (9) utilized data collected through calls to a teratology information service (Motherisk). The study from the U.S., by Fejzo et al. (14) used data from a larger investigation regarding hyperemesis gravidarum. Although the eligible studies mostly consisted of pregnant women with ondansetron exposure during the first trimester, the rates of first trimester exposure differed between the studies.

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Nevertheless, we focused on exclusively the first trimester exposures while pooling the data.

Pasternak et al. (11) and Andersen et al. (12) considered only first trimester ondansetron exposure,

while about 70% of the exposures in Danielsson et al. (13) and Colvin et al. (10) occurred during the first trimester. Fejzo et al. (14) described higher rates (>90%), and Einarson et al. (9) reported that most of the exposures in their study occurred between 4 and 9 week of pregnancy, but no rate was quantified.

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The eligible studies also used different types of control groups. Andersen et al. evaluated the rates of malformations in the metoclopramide-exposed pregnancies within the same cohort as the

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ondansetron exposed group (12), while Danielsson et al. also took a similar aprroach and asessed the

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outcomes of the meclizine-exposed pregnancies (13). Both approaches aimed to rule out confounding by indication. Pasternak et al. (11) and Colvin et al. (10) used a non-exposed control

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group whereas Einarson et al.(9) and Fejzo et al. (14) had two different control groups, diseasedmatched and unexposed, for comparison. Because such differences on the selection of the control

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group exists, we decided to undertake a sensitivity analysis by limiting the combination of results to

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studies which included control groups with similar characteristics. There were also two case-control studies. Anderka et al. used the National Birth Defects Prevention

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Study (NBDPS, 1997-2004) data to assess the link between the drugs used in the first trimester for NVP and possible malformations (16). Van Bennekom et al. (17) used two different datasets; Slone Birth Defects Study (BDS 1997– 2013) and the National Birth Defects Prevention Study (NBDPS)

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(2005–2009). Of importance, this study retrospectively evaluated the link between several different classes of drugs used for NVP and several organ specific malformations (17).

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The methodological quality assessment of the eligible studies with the Newcastle-Ottawa scale indicated high quality. The lowest score was received by Andersen et al. (12) since it was only published as an abstract. Therefore Pasternak et al. (11) was considered as eligible for our primary analysis among the the overlapping Danish studies since it received a much higher quality score. Meta-analysis of major and organ-specific congenital malformation rates in ondansetronexposed vs healthy controls

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Overall major congenital malformations Six studies assessing a total number of 5,148 ondansetron-exposed and 2,459,053 control infants were considered eligible for inclusion in this analysis (9-14). Because two of the studies were overlapping, Andersen et al. (11) was excluded in our primary analysis leaving a total of 3,914 ondansetron-exposed and 1,563,139 control infants. No significant increase in the rate of overall major congenital malformation was

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detected following ondansetron use during pregnancy (OR, 1.16; 95%, CI 0.92-1.45) in our primary analysis (Figure 2). However, the sensitivity analysis (including Andersen et al. (12) instead of Pasternak et al. (11) 3,915 exposed vs 2,454,121 control infants, slightly elevated the point estimate and altered the statistical significance (OR, 1.23; 95%, CI 1.02-1.48) (Figure 2). No significant heterogeneity among the studies were present for either analysis (incl. Pasternak et al.(11) P = 0.95, I-square = 0%, and incl. Andersen et al.(12) P = 0.91, I² = 0%).

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Figure 2. Meta-analysis of overall major congenital malformation rates in ondansetron-exposed vs

healthy controls Figure 2a. Forest plot of the primary analysis including Pasternak et al. Figure 2b.

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Forest plot of the sensitivity analysis substituting Pasternak et al. with Andersen et al.

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Heart defects

The same six studies were eligible for the analysis of heart defect risk (9-14). In the extraction of the data from the primary sources, we detected an inconsistency in the reported point estimate and confidence limits in one of the studies (13). Subsequent communication with the authors revealed a typing error in the upper limit of the reported confidence interval for heart defects (OR, 1.62; 95%, CI 1.04-2.14). The authors, in their recent erratum (27), corrected the upper confidence limit as 2.54 instead of 2.14. Considering this correction,

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the combined odds ratio for overall heart defect risk following ondansetron use was not significant (OR, 1.26; 95%, CI 0.90-1.77) (Figure 3). Similar to the major congenital malformation analysis above, the sensitivity analysis regarding the heart defects elevated the point estimate and altered the statistical significance (OR, 1.59; 95%, CI 1.14-2.21) (Figure 3). No significant heterogeneity existed for the investigated outcomes (incl. Pasternak et al.(11) P = 0.50, I-square = 0% and incl. Andersen et al.(12) P = 0.35, I² = 9%).

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Figure 3. Meta-analysis of heart defects in ondansetron-exposed vs healthy controls Figure 3a.

Forest plot of the primary analysis including Pasternak et al. Figure 3b. Forest plot of the sensitivity

Orofacial clefts

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analysis substituting Pasternak et al. with Andersen et al.

Three studies were eligible (10, 11, 14). No significant increase in the rates of orofacial clefts following

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ondansteron use during pregnancy were observed (OR, 0.89; 95% CI, 0.32-2.50) (Table 2). No significant heterogeneity was present (P = 0.97, I² = 0%).

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Isolated cleft palate

This outcome was only investigated by two case-control studies (16, 17). Cohort studies did not report the specific numbers of the infants with isolated cleft palate. Van Bennekom et al. (17)

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reported two different risk estimates from two seperate datasets which were used for the sensitivity analysis. Isolated cleft palate risk was not significantly associated with maternal ondansetron use in our primary analysis (OR, 1.13; 95% CI, 0.43-2.97) (Figure 4). The issue of significant heterogeneity (P = 0.0009; I² = 86%) necessitated a sensitivity analysis which yielded a conflicting result; pooled data from NBDPS (1997-2009) demonstrated a significant association (OR, 1.77; 95% CI, 1.15-2.72, P

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= 0.30; I² = 7%) (16, 17) whereas BDS (1997– 2013) data showed completely the opposite (OR, 0.40; 95% CI, 0.20-0.80) (17) (Figure 4). Figure 4. Meta-analysis of isolated cleft palate in ondansetron-exposed vs healthy controls. Figure 4a. Forest plot of the primary analysis with significant heterogeneity. Figure 4b. Forest plot of the sensitivity analysis using National Birth Defects Prevention Study dataset (NBDPS 1997-2009).

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Figure 4c. Forest plot of the sensitivity analysis using Slone Birth Defects Study dataset (BDS 1997–

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2013).

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Genitourinary malformations Four studies were eligible (9-11, 14). No significant increase in the rate of genitourinary malformation following ondansetron use during pregnancy was detected (OR, 1.55; 95% CI, 0.89-2.69) (Table 2). There was

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no significant heterogeneity (P = 0.30, I² = 0%). Hypospadias Four studies were eligible (9-11, 14). There was no significant increase in the rate of hypospadias following ondansetron use during pregnancy (OR, 1.65; 95% CI, 0.69-3.75) (Table 2). No significant heterogeneity was present (P = 0.90, I² = 0%).

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Meta-analysis of major and organ-specific congenital malformation rates in ondansetronexposed vs disease-matched controls Two studies were eligible (9, 14) for each particular outcome in this meta-analysis of which details are provided in Table 2b. Orofacial clefts could not be analyzed since no events were reported in Einarson et al.(9) leaving Fejzo et al.(14) as the only study to be considered. No significant increase in the rate of any particular outcome was detected in the pooled analysis. Higher pooled risk estimates and wider confidence

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limits were present for genitourinary malformations (OR, 2.01; 95% CI, 0.40-10.20, P = 0.39, I² = 0%) and particularly for hypospadias (OR, 4.01; 95% CI, 0.40-33.52, P = 0.62, I² = 0). The embryonic development periods for organ-specific congenital malformations which are investigated in our meta-analysis were

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presented in Table 3.

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Table 2. Meta-analysis of major and other organ-specific malformation rates ondansetron-exposed vs healthy and disease-matched controls. Table 2a. Meta-analysis of other organ-specific malformation rates in ondansetron-exposed vs healthy controls. Table 2b. Meta-analysis of major and organspecific congenital malformation rates in ondansetron-exposed vs disease-matched controls. Table 2a. No. of exposed events/total

No. of control events/total

Sample size

Odds Ratio (95%CI)

P value

P value for heterogeneity

I2 (%)

Orofacial clefts

3

4/2396

230/104,280

106,676

0.89 (0.32-2.50)

0.82

0.97

0

Genitourinary Malformations

4

19/2565

1380/104,442

107,007

1.55 (0.89-2.69)

0.12

0.81

0

Hypospadias

4

375/104,442

107,007

1.61 (0.69-3.75)

0.27

0.90

0

Table 2b.

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ED 10/2565

No. of studies

No. of exposed events/total

No. of control events/total

Sample size

Odds Ratio (95%CI)

P value

P value for heterogeneity

I2 (%)

Major Congenital Malformations

2

21/1121

10/601

1722

1.21 (0.56-2.58)

0.63

0.44

0

Heart defects

2

6/1121

2/601

1722

1.66 (0.30-9.09)

0.56

0.61

0

Genitourinary Malformations

2

6/1121

2/601

1722

2.01 (0.40-10.20)

0.40

0.39

0

Hypospadias

2

5/1121

0/601

1722

4.01 (0.48-33.52)

0.20

0.62

0

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Analysis

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No. of studies

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Table 3. Embryonic development week (s) of organ-specific congenital malformations investigated in our meta-analysis. Congenital malformations

Embryonic development week (s)

Heart defects Heart development

From the middle of week 3 until the end of week 8 (28)  Highly sensitive period for heart is from the middle of week 3 to week 6 (29)

Orofacial clefts Palate development

Genitourinary malformations Urinary tract development

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5th to 12th week (30)  Most critical period for palate is 6th to 9th week (30)  The critical period of cleft palate is also reported as 8th to 12th week and critical period of cleft lip with or without palate is 5th to 7th week in other studies (31)

3rd to 34th week (32)  No critical or sensitive period was defined (31).

Hypospadias

11th to 16th week (33) Critical period for hypospadias is 10th to 16th week (31)

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 

External genital organ development

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7th to 16th-17th week (34)  Most sensitive period is defined as the middle of week 7 until the end of week 9 (29)

Discussion

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In this meta analysis we observed that the pooled point estimates regarding overall major congenital malformation and heart defect risks increased and became significant when we undertook sensitivity

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analyses which substituted the results of two studies which utilised an overlapping datasource (Andersen et al. (12) and Pasternak et al. (11)). However, the results of our primary analysis which used the studies with

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the highest quality assessment score indicated that ondansetron use during pregnancy was not associated with significantly increased rates of overall major congenital malformations, heart defects, orofacial clefts, genitourinary malformations and hypospadias when exposed infants were compared with healthy or disease-

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matched controls. Data regarding the isolated cleft palate risk was heterogenous and conflicting, thus precluded us to reach any conclusions. Although non-significant, the effect size and the direction of the point estimates for genitourinary malformations and hypospadias in the ondansteron-exposed vs. healthy and

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disease-matched controls deserve attention in further studies. Our results regarding overall major congenital malformations in exposed vs. healthy or disease-matched controls are in line with the results of the previous cohort studies (9-14). No particular study to date has reported a significant increase in the rates of overall major congenital malformations. The highest point estimate regarding overall major congenital malformations was reported by Andersen et al (OR 1.3, 95% CI

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1.0–1.7) (12), inclusion of which in the sensitivity analysis, led to a slightly increased and significant pooled point estimate, in our meta-analysis. A very important point of debate among the previous cohort studies regarding ondansetron use during pregnancy is the consequent risk of heart defects. The rate of heart defects was not significantly elevated following ondansetron exposure during pregnancy in our primary analysis. However, similar to the issue with

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overall major congenital malformations, including Andersen et al. (12) instead of Pasternak et al. (11) led to a slightly elevated and significant point estimate.Two independent cohorts, Danielsson et al. (13) and Andersen et al. (14) reported a significant increase in the rates of heart defects previously. Danielsson et al. (13) reported an OR of 1.62 (95% CI 1.04 - 2.14) for heart defects, of which the upper confidence limit is corrected as 2.54 later by the authors via recently published erratum (27) triggered by our communication, and 2.05 (95% CI 1.19 - 3.28) for septum defects. Andersen et al. (12) reported an OR of 2.0 (1.3 - 3.1) for heart defects and this OR was much different from that of Pasternak et al. (a crude OR of 1.04, 95% CI 0.52–1.95) which

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used an overlapping dataset. Of note, a 2018 in vitro study which exposed gestational day 13 rat embryos to increasing doses of ondansetron identified that such exposures decreased the embryonic heart rate in a dose-

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dependent manner, and even produced some ventricular arrhythmias at the highest doses utilized (35).

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Taken in consideration with previously published animal teratology studies, which had suggested exposure to be related with arrhythmia-related anomalies (including cardiovascular and skeletal defects), the authors of

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the in vitro study suggested that the mechanism by which these anomalies may occur could be linked with cardiac Human Ether-a-go-go (hERG) channel ondansetron inhibition (35). Whilst this plausible biological mechanism may add weight to the notion that ondansetron use in early pregnancy increases the risk of

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cardiac anomalies in humans, further epidemiological surveillance is needed. Such research should utilise

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study designs and datasets which together address some of the key data limitations associated with the currently available studies. Once such data become available, the findings of this in vitro study may be more

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reliably extrapolated to inform on the human fetal risks of maternal ondansetron use in pregnancy. No cohort study to date has indicated an increase in the rate of orofacial clefts or isolated cleft palate following ondansetron use during pregnancy. However, a case-control study by Anderka et al. using

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data from the National Birth Defects Prevention Study (1997-2004) reported that infants with cleft palate were significantly more likely to be exposed to ondansetron in utero than healthy control

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infants (aOR 2.37; 95% CI, 1.18–4.76) though no association with cleft lip with or without cleft palate was identified (16). A recent case-control study by Van Bennekom et al. which was published first in the abstract form (17) which we used in our meta-analysis, and then published in the full text form during the submission phase of this manuscript (36), reported opposite findings among two different datasets regarding this issue (17, 36). Ondansetron exposure among infants with cleft palate was elevated in The National Birth Defects Prevention Study (NBDPS, the abstract version covers years 2005-2009, while the full text version covers the years 2005-2011)(36) whereas the Slone Birth

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Defects Study (BDS, the abstract version covers years 1997-2013 and the the full text version covers the years 1997– 2014) reported a significantly decreased exposure rate among infants with cleft palate (17, 36). These results caused a significant heterogeneity in our meta-analysis leading to a non-significant point estimate in the primary analysis. However, we detected a significant pooled point estimate when only the data from the National Birth Defects Prevention Study (1997-2004; 2005-2009) were considered (16, 17). Parker et al. also could not explain this discrepancy, in spite of

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conducting a number of sensitivity analysis, in their study (36). This positive association might be a result of multiple comparisons and warrants to be confirmed using a different dataset. The

retrospective nature of exposure ascertainment in these type of studies could theoretically introduce recall bias to the dataset, while multiple testing for associations between various different exposures and outcomes could introduce chance findings.

Our meta-analysis of cohort studies regarding the genitourinary malformations and hypospadias detected no

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significant increase in risk with ondansetron used during pregnancy when exposed infants were compared with healthy and disease matched controls, respectively. However, higher pooled estimates such as 2.01 and

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4.01 were computed in the latter analysis. Of importance, this analysis included two studies which did not

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deal seriously with the issue of confounding and comprising much smaller number of control infants. Nevertheless, the direction and the effect size of the pooled point estimates among comparisons with healthy

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and disease-matched controls showed a trend towards an increase. In addition, Colvin et al. (10) reported an OR of 6.2 (95% CI 2.0–19.5) for obstructive defects of renal pelvis and ureter following ondansetron exposure

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in their cohort study while Van Bennekom et al. (17) reported a significant association (OR 2.3, 95% CI 1.3– 4.0) between renal agenesis/dysplasia and ondansetron exposure in their case-control study (Slone Birth

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Defects Study 1997– 2013 dataset). Our pooled results, combined with these previous findings, warrant surveillance for genitourinary malformations and hypospadias in future studies.

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Our findings are generally in line with the systematic reviews published on this topic during the previous years (2, 37) and the recent systematic review by Lavecchia et al. which was published during the writing

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phase of this manuscript (38). However, our meta-analysis differs from all these studies in one major way that it also quantitatively pools the available data. The review by Lavecchia et al., includes one additional paper, a small retrospective study (39) which was not covered in our choice of databases, whereas our study

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also differently includes the study by Andersen et al. (12) which provokes further discussion. In addition, our study was able to reach the raw data, and therefore, it was possible to calculate the number of specific malformations in the studies by Colvin et al., (10) and Fejzo et al. (14) independently. Similarly to our study, Lavecchia et al. also emphasized the limitations and discrepancies regarding the current data (e.g. heart defects and cleft palate) with no significant safety concerns regarding major congenital malformations (38).

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Neurobehavioral outcome is an important yet understudied domain for the studies assessing the possible effects of medication use during pregnancy. Data regarding this domain is limited to one prospective cohort study and a prospective case-control study, the first of which reported no significant adverse effects in the ondansetron-exposed infants and children who were between 17 and 66 months of age (40). Of interest, some of the infants were also exposed to promethazine beside ondansetron in this study. The second study compared rates of maternal ondansetron use for hyperemesis gravidarum between mothers of infants with

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neurodevelopmental delay (n=99/138, 71.7%) and mothers of infants without delay (n=114/174, 65.5%), and found no statistically significant difference (P=0.294) (41) Given the limited number of studies and the small number of ondansetron-exposed pregnancies included in the respective analyses, this area undoubtedly requires further exploration.

Off-label ondansetron use among pregnant women is on a steep rise (18). Taylor et al. reported that the use increased from <1% of pregnancies in 2001 to 22.2% in 2014, with much of this increment attributable to the

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development of oral ondasetron preparations which first became available in 2006 (18). Therefore, making interventions for monitoring the off-label prescriptions and outcomes, such as establishing databases, may be

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an important source for the future studies investigating the birth outcomes following maternal ondansetron

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use.

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To mention a few strengths of our meta-analysis is important. There were some high quality cohort studies which adequately dealt with the issue of confounding. The sample size of the exposed and control groups particularly for overall major congenital malformations and heart defects were quite

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large and yielded relatively narrow confidence limits. The included studies retrieved data from three

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different geographical regions (Scandinavia, North America and Australia). However, a few important limitations should also be mentioned. The exact information regarding the exposure time windows, dose and duration were not reported in the majority of the studies which limits our ability to discuss

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the exposure with regard to the sensitive periods for congenital malformations. In addition, characteristics of the healthy and disease-matched control groups widely differed between studies. Besides, a few included studies were published as abstracts, precluding us from assessing the details

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of their methodology. Although studies retrieved the data from three different geographical regions, 60% of the data originated from Scandinavian pregnancy registries, with their inherent limitations,

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discussed elsewhere (42). In conclusion, the use of ondansetron during pregnancy was not associated with a significantly increased rate of overall major congenital malformations, heart defects, orofacial clefts, genitourinary malformations and hypospadias in our primary analysis. However, the observation of varying results regarding the statistical significance of the point estimates for overall major congenital malformations and heart defects depending on the studies which were included or excluded from combination in this meta-analysis warrants the need for

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continued surveillance. The issue with cleft palate remains to be further investigated while genitourinary malformations and hypospadias should also deserve attention in future studies. Future studies should also strive to include detailed information regarding gestational age, dose and duration of exposure in order to increase our ability to assess the safety more accurately.

In addition, neurobehavioral outcomes after in

utero ondansetron exposure is a potential area which requires further exploration for which very limited data exist currently. Future studies should also be designed to differentiate the increased fetal risks which

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occur as a consequence of hyperemesis gravidarum, for instance Binder phenotype in the infant through causing maternal vitamin K deficiency, to lessen the impact of confounding by indication (43). Ondansetron should not be used as the first choice of treatment for NVP in the first trimester/ period of organogenesis until more safety data is available. Nevertheless, for the pregnant women for whom it is clinically indicated, the results of this meta-analysis may be reassuring since the clinical significance of effect sizes for which the uncertainties exist seems low. A second level fetal USG targeting particularly heart defects, orofacial clefts and

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genitourinary defects would be convenient following a first trimester exposure.

After submission of this manuscript for publication, the authors became aware of two new studies (44, 45)

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which had investigated the risk of specific congenital malformations following maternal ondansetron use in

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early pregnancy. These newer studies were not included in the present meta-analysis due to the timing of the original search and data extraction/collection as detailed in the methods. Whilst it is considered unlikely that

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the addition of these new study data would change the observations regarding overall and cardiac malformation risks (see Appendix for a brief summary), it is likely that they could have suggested a small but statistically significant increased risk of orofacial cleft following maternal first trimester ondansetron use.

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However, our conclusion regarding the use of ondansetron in pregnant women remains same; ondansetron

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should not be considered as a first choice treatment for NVP in the first trimester, however, since the absolute risks seem low, its use may remain justifiable on a case-by-case basis where first choice medications have

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failed to control the maternal symptoms. Acknowledgements: We sincerely appreciate Lyn Colvin and Marlena S. Fejzo for providing us the

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unpublished data regarding their studies. We also would like to express our sincere thanks to Ester Garne from JRC-EUROCATCentral Registry for providing us consultation regarding the classification

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of malformations. The preliminary findings of this study were presented in annual meeting of European Network of Teratology Information Centers in Budapest 2017 and an abstract was published in Reproductive Toxicology (2017; 72: 203–204. Funding/Support: No funding was provided for the specific purpose of the performance of this study. This study was conducted by researchers from Terafar - Izmir Katip Celebi University

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Teratology Information, Training and Research Center, The UK Teratology Information Service and Mothersafe, member organisations of the European Network of Teratology Information Services (ENTIS). The financial support for these organisations is provided from either national or local government funds.

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Conflict of Interest Statement: All authors have completed the Unified Competing Interest Form (available on request from the corresponding author) and declare no support from any organization for the submitted work, no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years and no other relationships or activities that could appear to have influenced the submitted work.

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Contribution statement: It is the opinion of the lead study author that all study authors contributed equally

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to the performance of the research detailed in this manuscript.

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Transparency declaration: As lead study author Y.C.K affirms that the manuscript is an honest, accurate,

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and transparent account of the study being reported; that no important aspects of the study have been

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omitted; and that any discrepancies from the study as planned have been explained.

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Appendix

The first of the newer studies utilised data from the Truven Health MarketScan dataset of anonymised health insurance records which was collected in the USA between 2000 and 2014, and

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provided a very large sample size of over 860,000 mother-child pairs (44). The study included up to 76,330 first trimester ondansetron-exposed mother-child pairs as defined by either prescription data

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or with confirmed medical administration, and 5,557 with first trimester medical administration only. The study findings described statistically significant increased risks of cardiac malformations following ondansetron exposure as defined by medical administration data, specifically including

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septal defects overall, ventricular septal defects, atrial septal defects and atrioventricular septal defects. However, when exposure was defined by prescription and medical administration data combined, these findings only remained of borderline statistical significance for septal defects overall and atrioventricular septal defects specifically. No statistically significant increased risks of orofacial clefts overall or specifically cleft lip alone, cleft palate alone, or cleft lip with or without cleft palate were observed. Exploratory analyses in the dataset also identified associations with diaphragmatic hernia (based on both exposure defined from medical administration alone and when also combined Page 7

with prescription data), and laryngeal clefting, craniosynostosis and renal collecting system defects using the combined medical administration and prescription data to define exposure. The second study utilised data from the Medicaid Analytic eXtract of social health insurance claims data in the USA from 2000 to 2013 (45). Again the study included a very large sample of more than 1.8 million mother-child pairs, with more than 88,000 exposed to ondansetron in the first trimester

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(defined by pharmacy dispensing records) and utilised propensity score methods to account for a

large number of possible data confounders. The study results did not provide evidence of statistically significant increased rates of overall malformation, overall cardiac malformation or specifically

ventricular septal defects, atrial septal defects and atrioventricular septal defects in comparison with either unexposed population or disease-matched (exposed to other anti-emetics) controls. However, small but statistically significant increased risks of any oral cleft were observed in comparison with

both of these control groups. A further analysis of the specific types or oral clefts suggested a possible

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small increased risk of cleft palate specifically which was statistically significant in a sensitivity analysis which utilised proxy measures to control for confounding by indication. Exploratory

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analyses also suggested statistically significant increased risks of ear and respiratory malformations.

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Considering the findings relating to overall malformation risk, it is probable that the weight of the Huybrechts et al. study would minimise any difference in the risk estimates following the

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substitution of the Pasternak et al. study data with that provided from Andersen et al. As such, it is unlikely that either the primary or secondary meta-analysis would have identified increased risks for

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overall malformation rate.

Given that the findings of the two studies relating to risks of overall cardiac malformation are

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conflicting, the expected results from inclusion in a meta-analysis are less predictable. Given the slightly larger sample size of the Huybrechts et al. study, it is possible that the increased risk

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suggested from the Zambelli-Weiner et al. analysis would have been attenuated on combination. Furthermore, and as with the overall malformation data, it is likely that the sample sizes of the Zambelli-Weiner et al. and Huybrechts et al. studies would have limited any differences in risk

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estimates with Pasternak et al. and Andersen et al. study data substitution. Finally, as the data provided from Zambelli-Weiner et al. and Huybrechts et al. was provided from

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longitudinal cohort studies, these data would not have been suitable to pool with those provided from the case-control studies as described in this meta-analysis (16, 17). However, it is possible that combination of the data provided from Zambelli-Weiner et al., which described a non-significant but increased risk of orofacial clefts , with that provided from Huybrechts et al., which described a small but statistically significant increased risk, may have also described a small but statistically significant increased risk of orofacial clefts overall.

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References 1. Einarson TR, Piwko C, Koren G. Quantifying the global rates of nausea and vomiting of pregnancy: a meta analysis. J Popul Ther Clin Pharmacol. 2013; 20(2): e171-83. 2. Kennedy D. Ondansetron and pregnancy: Understanding the data. Obstet Med. 2016; 9(1): 28-33. 3. Maltepe C. Surviving morning sickness successfully: from patient's perception to rational management. J Popul Ther Clin Pharmacol. 2014; 21(3): e555-64. 4. Niebyl JR, Briggs GG. The pharmacologic management of nausea and vomiting of pregnancy. J Fam Pract. 2014; 63(2 Suppl): S31-7. 5. Munch S, Korst LM, Hernandez GD, Romero R, Goodwin TM. Health-related quality of life in women with nausea and vomiting of pregnancy: the importance of psychosocial context. J Perinatol. 2011; 31(1): 10-20. 6. Mazzotta P, Stewart D, Atanackovic G, Koren G, Magee LA. Psychosocial morbidity among women with nausea and vomiting of pregnancy: prevalence and association with anti-emetic therapy.J Psychosom Obstet Gynaecol. 2000 Sep;21(3):129-36. 7. Chaffee BJ, Tankanow RM. Ondansetron--the first of a new class of antiemetic agents. Clin Pharm. 1991 Jun;10(6):430-46. 8. Maltepe C, Koren G. The management of nausea and vomiting of pregnancy and hyperemesis gravidarum--a 2013 update. J Popul Ther Clin Pharmacol. 2013;20(2):e184-92. 9. Einarson A, Maltepe C, Navioz Y, Kennedy D, Tan MP, Koren G. The safety of ondansetron for nausea and vomiting of pregnancy: a prospective comparative study. BJOG. 2004;111(9):940-3. 10. Colvin L, Gill AW, Slack-Smith L, Stanley FJ, Bower C. Off-label use of ondansetron in pregnancy in Western Australia. Biomed Res Int. 2013;2013:909860. 11. Pasternak B, Svanström H, Hviid A. Ondansetron in pregnancy and risk of adverse fetal outcomes.N Engl J Med. 2013 Feb 28;368(9):814-23. 12. Andersen JT, Jimenez-Solem E, Andersen NL, Poulsen HE. Ondansetron use in early pregnancy and the risk of congenital malformations - a register-based nationwide cohort study. Abstract 25 ISPE 2013; Pharmacoepidemiology and Drug Safety, October 2013 13. Danielsson B, Wikner BN and Kallen B. Use of ondansetron during pregnancy and congenital malformations. Reprod Toxicol 2014; 50: 134–137. 14. Fejzo MS, MacGibbon KW, Mullin PM. Ondansetron in pregnancy and risk of adverse fetal outcomes in the United States. Reprod Toxicol. 2016;62:87-91. 15. Asker C, Wikner BN and Kallen B. Use of antiemetic drugs during pregnancy in Sweden. Eur J Clin Pharmacol 2005; 61: 899–906. 16. Anderka M, Mitchell AA, Louik C, Werler MM, Hernández-Diaz S, Rasmussen SA; National Birth Defects Prevention Study. Medications used to treat nausea and vomiting of pregnancy and the risk of selected birth defects. 17. Van Bennekom CM, Park SE, Anderka M, Louik C, Mitchell AA. Ondansetron for the treatment of nausea and vomiting of pregnancy and the risk of birth defects. Pharmacoepidemiol Drug Saf 2015;24:401–2. 18. Taylor LG, Bird ST, Sahin L, Tassinari MS, Greene P, Reichman ME, Andrade SE, Haffenreffer K, Toh S. Antiemetic use among pregnant women in the United States: the escalating use of ondansetron.Pharmacoepidemiol Drug Saf. 2017;26(5):592-596. 19. Moher D, Liberati A, Tetzlaff J, Altman DG for the PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ. 2009; 339: b2535.

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20. Stroup DF, Berlin JA, Morton SC, et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of observational studies in epidemiology (MOOSE) group. JAMA. 2000;283(15):2008-2012. 21. Wells G, Shea B, O’Connell D, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp. Accessed Jan 21, 2016.

SC RI PT

22. European Surveillance Of Congenital Anomalies. EUROCAT Subgroups of Congenital

Anomalies [homepage on the Internet]. c2014 [updated 2016 Aug 08; cited 2016 Sep 21]. Available from http://www.eurocat-network.eu/content/EUROCAT-Guide-1.4-Section3.3.pdf

23. European Surveillance Of Congenital Anomalies. Minor Anomalies for Exclusion [homepage

U

on the Internet]. c2013 [updated 2014 Oct 14; cited 2016 Sep 21]. Available from

N

http://www.eurocat-network.eu/content/EUROCAT-Guide-1.4-Section-3.2.pdf 24. The Cochrane Collaboration. Cochrane handbook for systematic reviews of interventions,

A

version 5.1.0. 2011.

M

http://handbook.cochrane.org/chapter_9/9_4_3_2_the_generic_inverse_variance_outcome_t ype_in_revman.htm. Accessed Jan 21, 2016. 25. Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses.

D

BMJ. 2003;327(7414):557-560.

TE

26. Lau J, Ioannidis JP, Terrin N, Schmid CH, Olkin I. The case of the misleading funnel plot. BMJ. 2006;333(7568):597-600.

27. Danielsson B, Wikner BN, Källén B. Erratum to "Use of ondansetron during pregnancy and

EP

congenital malformations in the infant" [Reprod. Toxicol. 50C (2017) 134-137]. Reprod Toxicol. 2017 Aug;71:176. 28. File:Human-critical periods of development.jpg - Embryology [Internet].

CC

Embryology.med.unsw.edu.au. [cited 20 December 2018]. Available from: https://embryology.med.unsw.edu.au/embryology/index.php/File:Human-

A

critical_periods_of_development.jpg

29. Appendix 2. Germ Layer Derivatives - Review of Medical Embryology Book - LifeMap Discovery [Internet]. Discovery.lifemapsc.com. [cited 20 December 2018]. Available from: https://discovery.lifemapsc.com/library/review-of-medical-embryology/appendix-2-germlayer-derivatives 30. Shkoukani MA, Lawrence LA, Liebertz DJ, Svider PF. Cleft palate: a clinical review. Birth Defects Res C Embryo Today. 2014 Dec;102(4):333-42

Page 10

31. Czeizel AE. Specified critical period of different congenital abnormalities: a new approach for human teratological studies. Congenit Anom (Kyoto). 2008 Sep;48(3):103-9. 32. Hindryckx A, De Catte L. Prenatal diagnosis of congenital renal and urinary tract malformations. Facts Views Vis Obgyn. 2011;3(3):165-74. 33. Blaschko SD, Cunha GR, Baskin LS. Molecular mechanisms of external genitalia development. Differentiation. 2012 Oct;84(3):261-8.

SC RI PT

34. Yiee JH, Baskin LS. Penile embryology and anatomy. ScientificWorldJournal. 2010 Jun 29;10:1174-9.

35. Danielsson B, Webster WS, Ritchie HE. Ondansetron and teratogenicity in rats: Evidence for

a mechanism mediated via embryonic hERG blockade. Reprod Toxicol. 2018 Oct;81:237-245. 36. Parker SE1, Van Bennekom C, Anderka M, Mitchell AA; National Birth Defects Prevention Study. Ondansetron for Treatment of Nausea and Vomiting of Pregnancy and the Risk of Specific Birth Defects. Obstet Gynecol. 2018 Aug;132(2):385-394.

U

37. Carstairs SD. Ondansetron Use in Pregnancy and Birth Defects: A Systematic Review. Obstet Gynecol. 2016 May;127(5):878-83.

N

38. Lavecchia M, Chari R, Campbell S, Ross S. Ondansetron in Pregnancy and the Risk of

A

Congenital Malformations: A Systematic Review. J Obstet Gynaecol Can. 2018 Jul;40(7):910918.

M

39. Özdemirci Ş, Akpınar F, Bilge M, Özdemirci F, Yılmaz S, Esinler D, Kahyaoğlu İ. The safety of ondansetron and chlorpromazine for hyperemesis gravidarum in first trimester pregnancy.

D

Gynecology Obstetrics & Reproductive Medicine [Online], 20.2 (2014): n. pag. Web. 2 Jan. 2019.

TE

40. Larrimer MB, Dajani NK, Siegel ER, Eswaran H, Newport DJ, Stowe ZN. Antiemetic medications in pregnancy: a prospective investigation of obstetric and neurobehavioral

EP

outcomes. Am J Obstet Gynecol. 2014 Mar;210(3):270.e1-7. 41. Fejzo MS, Magtira A, Schoenberg FP, Macgibbon K, Mullin PM. Neurodevelopmental delay in children exposed in utero to hyperemesis gravidarum. Eur J Obstet Gynecol Reprod Biol.

CC

2015 Jun;189:79-84.

42. V. Ehrenstein, H.T. Sørensen, L.S. Bakketeig, L. Pedersen, Medical databases in studies of drug

A

teratogenicity: methodological issues, Clin. Epidemiol. 2 (2010) 37–43.

43. Lane AS, Stallworth JL, Eichelberger KY, Trofatter KF. Vitamin K Deficiency Embryopathy from Hyperemesis Gravidarum. Case Rep Obstet Gynecol. 2015;2015:324173. 44. Zambelli-Weiner, A., C. Via, M. Yuen, D.J. Weiner, and R.S. Kirby, First trimester ondansetron exposure and risk of structural birth defects. Reprod Toxicol, 2018; 83: 14-20. 45. Huybrechts, K.F., Hernández-Díaz, S., Straub, L., Gray, K.J., Zhu, Y., Patorno, E., Desal, R.J., Mogun, H., and Bateman, B.T. Association of maternal first-trimester ondansetron use with cardiac malformations and oral clefts in offspring. JAMA, 2018; 320(23): 2429-2437 Page 11

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