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Perinatal outcomes in 521 gestations after fresh and frozen cycles: a secondary outcome of a randomized controlled trial comparing GnRH antagonist versus GnRH agonist protocols
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ARTICLE
Perinatal outcomes in 521 gestations after fresh and frozen cycles: a secondary outcome of a randomized controlled trial comparing GnRH antagonist versus GnRH agonist protocols BIOGRAPHY
Dr Claudia Tomás has been a Fertility Consultant at the Fertility Center of Assisted Reproduction, Hospital Garcia de Orta, Portugal since 2017, and currently in the ReproUnion/ESHRE Fellowship programme in the Fertility Clinic, Copenhagen University Hospital, Denmark. Her areas of research activity include perinatal outcomes, reproductive endocrinology and fertility preservation. Claudia Tomás1,3,*, Mette Toftager1, Kristine Løssl1, Jeanette Bogstad1, Lisbeth Prætorius2, Anne Zedeler2, Thue Bryndorf2, Anders Nyboe Andersen1, Anja Pinborg1 KEY MESSAGE
Perinatal outcomes are similar after the GnRH antagonist versus GnRH agonist protocols for ART treatments. The choice of the GnRH analogue should be based solely on optimizing clinical and safety aspects of the ovarian stimulation per se, as perinatal outcomes are similar in the two protocols. ABSTRACT
Research question: Are perinatal outcomes different after treatment with the gonadotrophin-releasing hormone (GnRH) antagonist versus the long GnRH agonist protocol for IVF? Design: Perinatal outcomes were secondary outcomes in a large Phase IV, dual-centre, open-label, randomized controlled trial to compare GnRH antagonist and long GnRH agonist protocols in women <40 years undergoing their first assisted reproductive technology treatment. Women (n = 1050) were randomized in a ratio 1:1 from January 2009 to December 2013 and followed until December 2016. All fresh and frozen embryo transfer (FET) cycles from a single oocyte aspiration, resulting in a gestation (human chorionic gonadotrophin >10 IU/l) were included (n = 521). Data were analysed to compare preterm birth [PTB] (<37 weeks), very PTB (<32 weeks), low birthweight [LBW] (<2500 g) and very LBW (<1500 g) rates among singleton live births in GnRH antagonist versus agonist protocol. Results: Similar perinatal outcomes were found after both protocols. In singletons after fresh embryo transfer, mean gestational age at delivery was 39.1 ± 2.49 versus 39.3 ± 1.90 (P = 0.67) and very PTB rates 1.9% versus 0% (P = 0.17). Mean birthweight was 3264 ± 662 g in the antagonist and 3341 ± 562 g in the agonist group (P = 0.37). LBW was found in 12.4% versus 7% (P = 0.19) and very LBW in 2.9% versus 1% (P = 0.34). In FET cycles, the perinatal outcomes were similar. Small for gestational age and large for gestational age rates were similar in both protocols for singleton live births after fresh and FET. Conclusions: Perinatal outcomes are similar after the GnRH antagonist versus GnRH agonist protocols for IVF. The choice of the GnRH analogue in ovarian stimulation should be based solely on optimizing the chance of pregnancy and not on risks in perinatal outcomes. 1 The
Fertility Clinic, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark of Obstetrics and Gynaecology, Fertility Clinic, Copenhagen University Hospital Hvidovre, Denmark of Infertility and Medically Assisted Reproduction, Hospital Garcia de Orta, Almada, Portugal
2 Department 3 Centre
© 2019 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved. *Corresponding author. E-mail address: [email protected] (C Tomás). https://doi.org/10.1016/j.rbmo.2019.05.010 1472-6483/© 2019 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved. Declaration: The authors report no financial or commercial conflicts of interest.
KEYWORDS
ART GnRH agonist GnRH antagonist Perinatal outcomes
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INTRODUCTION
MATERIALS AND METHODS
he goal of assisted reproductive technology (ART) is to achieve a healthy live-born child, with as few complications as possible during treatment, pregnancy and delivery. However, several studies have shown ART pregnancies to be associated with a higher risk of perinatal complications compared with naturally conceived pregnancies (Sunkara et al., 2016) and also, women undergoing ART treatment are on average older and have various comorbidities before conception (Henningsen and Pinborg, 2014).
Study design Pregnancy and perinatal outcome were secondary outcomes in a large Phase IV, dual-centre, open-label, randomized controlled trial (RCT), with the objective to compare the GnRH antagonist and the long GnRH agonist protocols in an unselected population referred for their first ART treatment. Women (n = 1050) were randomized in a ratio of 1:1 over a period of 5 years from January 2009 to December 2013 and were followed for 3–8 years, until December 2016. Study design including inclusion and exclusion criteria are described in two previous publications (Toftager et al., 2016, 2017).
T
Evidence shows that children born after ART treatment have an increased risk of adverse perinatal outcomes such as preterm birth (PTB), low birthweight (LBW), small for gestational age (SGA) and large for gestational age (LGA) (Henningsen and Pinborg, 2014; Kamath MS et al., 2018; Sunkara et al., 2016). Different perinatal risk profiles are associated with different ART treatments, frozen embryo transfer (FET) being associated with a higher risk of singletons being LGA and macrosomic (Henningsen and Pinborg, 2014). Poor perinatal outcomes are known to be associated not only with increased neonatal morbidity but also with long-term health outcomes, including an increased risk of diseases related to metabolic syndrome (Ozgur et al., 2015). The widespread use of elective single embryo transfer (eSET) has considerably improved perinatal and obstetric outcomes in ART treatment; however, singleton pregnancies after ART treatment still carry an increased risk of perinatal complications (Luke et al., 2017a). One additional factor that may influence the outcome of pregnancies is the ovarian stimulation protocol. It is known that the GnRH antagonist protocol and GnRH agonist protocol differ regarding number of oocytes retrieved, oestradiol peak levels and ovarian hyperstimulation syndrome (OHSS) risks, besides similar live birth rates (Toftager et al., 2016; Xiao et al., 2014). Hence these two different ovarian stimulation regimens may also result in different perinatal outcomes. The aim of this study was to explore perinatal outcomes in gestations following the GnRH antagonist versus the agonist cycle.
Participants All fresh and FET cycles leading to a gestation, human chorionic gonadotrophin (HCG) >10 IU/l (13–15 days after transfer) were included (n = 521). All women were under 40 years of age and referred for their first ART treatment cycle at two public fertility clinics in Denmark: Hvidovre Hospital, Copenhagen and Dronninglund Hospital, Aalborg. All women underwent one complete ART cycle including fresh and subsequent frozen–thawed embryo transfers. FIGURE 1 provides a chart of all included pregnancies; in total there were 347 gestations with positive HCG after fresh transfer, 174 gestations after FET, 225 ongoing pregnancies after fresh and 115 after FET (FIGURE 1). Outcome measures Positive HCG and ongoing pregnancy were registered at visits to the fertility clinic and documented in the electronic case report form. Perinatal outcomes were based on a maternal self-reported questionnaire posted to the mother after delivery and returned to the fertility clinic. Additional information was obtained from the medical birth files. A miscarriage was defined as the spontaneous loss of a pregnancy before gestational age 22 + 0. A stillbirth was the delivery of a deceased infant after 22 + 0 weeks of gestation. A live birth, defined as both singleton and twin births, was the delivery of a live-born child after 22 + 0 weeks. PTB was defined as a live birth at <37 + 0 weeks of gestation and very preterm birth (VPTB) as a live birth <32 + 0 weeks of gestation. LBW was a live infant delivered with a weight of <2500 g, and very LBW (VLBW) was
a live infant delivered with a weight of <1500 g. The classic definition for SGA and LGA is a fetal birthweight less than or equal to the 10th and more than or equal to the 90th percentile for a given gestational age, respectively (Marsál et al., 1996). Statistical methods Only cycles resulting in a gestation (HCG >10 IU/l) after fresh embryo transfer and/or FET were included in this study. Data are presented as mean and SD for continuous variables and compared with Student's t-test. For proportions the chi-squared test was used (or the likelihood ratio test if the former was not possible). To avoid the bias of twins, only singletons were compared regarding perinatal outcomes. A P-value <0.05 was considered statistically significant. Data were analysed using SPSS Statistics for Windows, Version 23 (IBM Corp., Armonk, NY, USA). Ethics The RCT study was approved by the Danish Scientific Ethics Committee, Capital Region of Denmark, Protocol #: H-B-2008-109, and approved by the Danish Medicines Agency, EudraCT #: 2008-005452-24. Registration ID on ClinicalTrials.gov: NCT00756028. The study is reported according to the CONSORT statements. All subjects provided written informed consent.
RESULTS As shown in TABLE 1, women that were pregnant after fresh embryo transfer had comparable baseline characteristics and demographic parameters in terms of age, body mass index (BMI), smoking status, previous pregnancy or delivery, duration of infertility and the distribution of primary cause of infertility, between the GnRH antagonist and GnRH agonist groups (NS). Severe OHSS (grades 4 and 5) occurred in 7.7% versus 13.3% in the antagonist versus the agonist group, respectively. The endometrial preparation before FET was performed with a natural modified cycle in 81.6% of the antagonist versus 80.3% of the agonist cycles or with an artificial cycle in 18.4% versus 18.4% (P = 0.99). The mean number of frozen embryos transferred was 1.55 ± 0.50 in both antagonist and agonist protocols. shows pregnancy and delivery outcomes after antagonist and agonist TABLE 2
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FIGURE 1 Flow chart of overview of the outcomes (ET = embryo transfer; FET = frozen embryo transfer; GnRH = gonadotrophin-releasing
hormone).
TABLE 1 BASELINE CHARACTERISTICS AND CYCLE RESULTS OF PREGNANT WOMEN AFTER FRESH EMBRYO TRANSFER GnRH antagonist group (n = 181)
GnRH agonist group (n = 166)
Age at inclusion, mean (SD)
32.0 (4.2)
32.0 (4.1)
BMI (kg/m²), mean (SD)
24.7 (4.1)
24.4 (4.0)
Non-smoker
169 (93.4)
154 (92.8)
Actual smoker
12 (6.6)
12 (7.2)
Previous pregnancya
57 (31.5)
44 (26.5)
13 (7.2)
9 (5.4)
Male
80 (44.2)
81 (48.8)
Female
37 (20.4)
36 (21.7)
Unexplained
50 (27.6)
42 (25.3)
Other causes
14 (7.7)
7 (4.2)
Duration of infertility (years), mean (SD)
2.3 (1.7)
2.5 (1.7)
ICSI
60 (33.1)
61 (36.7)
IVF
121 (66.9)
105 (63.3)
Oestradiol level on the day of HCG (nmol/ml), mean (SD)
3.1 (2.3)
4.3 (2.4)
Number of fresh transferred embryos, mean (SD)
1.2 (0.4)
1.2 (0.4)
Number of frozen embryos, median
1
2
Severe OHSS (grades 4 and 5)
14 (7.7)
22 (13.3)
Smoking status:
Previous
deliverya
Primary cause of infertility:
Intended IVF method:
Data are presented as n (%) unless otherwise stated. a Including
spontaneous and fertility treatments other than IVF/ICSI. There were no statistically significant differences between the two groups.
BMI = body mass index; GnRH = gonadotrophin-releasing hormone; HCG = human chorionic gonadotrophin; ICSI = intracytoplasmic sperm injection; OHSS = ovarian hyperstimulation syndrome.
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TABLE 2 PREGNANCY OUTCOMES AFTER FRESH AND FROZEN EMBRYO TRANSFER IN EITHER GNRH ANTAGONIST OR AGONIST PROTOCOL WITH STRATIFICATION BY FRESH AND FROZEN EMBRYO TRANSFER Fresh embryo transfer
Frozen embryo transfer
GnRH antagonist group (n = 181)
GnRH agonist group (n = 166)
Z
95% CI
GnRH antagonist group (n = 98)
GnRH agonist group (n = 76)
Z
95% CI
Early (<12 weeks)
58 (32.0)
57 (34.3)
–0.34
(–0.12; 0.08)
29 (29.6)
24 (31.6)
–0.28
(–0.16; 0.12)
Late (>12 weeks)
4
(2.2)a
2 (1.2)
0.72
(–0.02; 0.04)
0
2 (2.6)
–1.62
(–0.06; 0.01)
Ectopic pregnancy
1 (0.6)
0
0.96
(–0.01; 0.02)
2 (2.0)
2 (2.6)
–0.26
(–0.05; 0.04)
Ongoing pregnancy >22 weeks
118 (65.2)
107 (64.5)
0.14
(–0.09; 0.11)
67 (68.4)b
48 (63.2)b
0.72
(–0.09; 0.19)
Singleton pregnancy
105 (58.0)
100 (60.2)
–0.42
(–0.13; 0.08)
60 (61.2)
42 (55.3)
0.79
(–0.09; 0.21)
Twin pregnancy
11 (6.1)
6 (3.6)
1.06
(–0.02; 0.07)
6 (6.1)
4 (5.3)
0.24
(–0.06; 0.08)
Live birth
116 (64.1)
106 (63.9)
0.05
(–0.10; 0.10)
66 (67.3)
46 (60.5)
0.93
(–0.08; 0.21)
Stillbirth (>22 weeks)
2 (1.1)
1 (0.6)
0.50
(–0.01; 0.02)
0
0
–
–
Miscarriage:
c
All P-values are non-significant (P > 0.05). Data presented as n (%) unless otherwise stated. a One
late miscarriage for medical interruption of pregnancy for trisomy 21.
b Three c Twins
cases lost in follow-up in frozen embryo transfer (one in the antagonist group, two in the agonist group). counts as one live birth.
CI = confidence interval; GnRH = gonadotrophin-releasing hormone.
protocols stratified after fresh and FET. No statistical differences were observed in pregnancy outcomes between the GnRH antagonist and agonist cycles either in fresh or in FET pregnancies. Only three cases of ongoing pregnancy were lost to follow-up. Perinatal outcomes are depicted in TABLE 3 . The gestational age at delivery after fresh embryo transfer was 39.1 ± 2.5 and 39.3 ± 1.9 weeks in the antagonist versus the agonist group (P = 0.67). Among the PTB (9.5% versus 10%; P = 0.91), the majority had a late PTB. Only 1.9% and 0% (P = 0.17) had a VPTB in the antagonist versus the agonist group. The mean birthweight of singleton live births after fresh embryo transfer was 3263.5 ± 661.8 g in the antagonist group and 3341.3 ± 562.1 g in the agonist group (P = 0.37); 12.4% versus 7% (P = 0.19) had a LBW, and 2.9% versus 1% (P = 0.34) a VLBW. According to Marsál standard curves, SGA was found in 6.7% versus 2% (P = 0.10) and LGA in 0.95% versus 4% (P = 0.16) in the GnRH antagonist versus GnRH agonist protocols, respectively. In pregnancies after FET similar results were found except that the mean birthweight was 3403.8 ± 641.9 g versus 3640.6 ± 484.6 g and P < 0.05 in the antagonist and agonist groups, respectively. However, if the second child delivery after a FET was excluded (9 in the antagonist protocol and 10
in the agonist protocol), the mean birthweight in the antagonist and agonist protocols were similar (3369.7 ± 672.4 g versus 3580.7 ± 509.4 g, P = 0.13). No differences were found in either SGA or LGA rates between the protocols. Obstetric complications were registered in very few cases and no differences were observed either in fresh or FET (TABLE 3). No neonatal deaths or congenital malformations were reported among singletons.
DISCUSSION No differences were observed in perinatal outcomes after GnRH antagonist versus GnRH agonist when viewing complete ART treatment cycles. The clinical consequence is that the choice of protocol for ovarian stimulation should not be determined by perinatal concerns, but solely on optimizing the balance between chance of pregnancy and risk of OHSS. Many factors affect pregnancy and perinatal outcomes, both directly and indirectly, and the causes of the poorer perinatal outcomes following IVF are most probably multifactorial (Berntsen et al., 2019). Both subfertility per se and IVF treatment, including ovarian stimulation and embryo culture techniques, have been suggested as risk factors for adverse perinatal and
obstetric outcomes (Magnusson et al., 2018; Pinborg et al., 2013). The antagonist and the long agonist protocols differ in several respects. The total gonadotrophin doses used are higher, the length of stimulation longer, pre-trigger oestradiol levels higher, number of aspirated oocytes higher, and the risk of OHSS is increased with the GnRH agonist protocol. Based on data from sibling studies, comparing children born after fresh and frozen cycles, it is known that the birthweight is lower after ovarian stimulation (Henningsen et al., 2011; Romundstad et al., 2008). All factors that can cause changes in the oocyte and endometrium lead to epigenetic changes in early embryo development and implantation and may change pregnancy and perinatal outcomes (Pinborg et al., 2013). Pereira et al. 2017 showed that supraphysiologic oestradiol was an independent predictor of LBW in full-term singletons born after fresh embryo transfer. In fresh cycles, the elevated oestradiol level on the day of the trigger is closely related also to SGA and pre-eclampsia due to abnormal early placentation (Imudia et al., 2012). Consistent with these findings, Sunkara et al. (2015) showed, based on the national UK data from the Human Fertilisation and Embryology Authority, that women with more than 20 aspirated oocytes have a higher risk of PTB and LBW. In contrast, the study by
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TABLE 3 PERINATAL OUTCOMES IN SINGLETONS AFTER BOTH FRESH AND FROZEN EMBRYO TRANSFER IN EITHER GNRH ANTAGONIST OR AGONIST PROTOCOL WITH STRATIFICATION BY FRESH AND FROZEN EMBRYO TRANSFER Fresh embryo transfer
Frozen embryo transfer
GnRH antagonist group (n = 105)
GnRH agonist group (n = 100)
Z
95% CI
GnRH antagonist group (n = 60)
GnRH agonist group (n = 42)
Z
95% CI
Complications during pregnancya
15 (14.3)
16 (16.0)
–0.34
(–0.12; 0.08)
8 (13.3)
3 (7.1)
0.99
(–0.05; 0.18)
Gestational age at delivery, mean (SD)
39.1 (2.5)
39.3 (1.9)
–0.43e –
39.3 (3.0)
39.7 (1.5)
–0.74e –
Induction of labour
22 (21.0)
24 (24.0)
–0.52
(–0.15; 0.08)
14 (23.3)
13 (31.0)
–0.86
(–0.25; 0.10)
Term delivery
95 (90.5)
90 (90.0)
0.12
(–0.08; 0.09)
53 (88.3)
39 (92.9)
–0.76
(–0.16; 0.07)
Preterm birth (<37 weeks)
10 (9.5)
10 (10.0)
–0.16
(–0.09; 0.08)
7 (11.7)
3 (7.1)
0.76
(–0.07; 0.16)
Very preterm birth (<32 weeks)
2 (1.9)
0
1.39
(–0.01; 0.05) 3 (5.0)
0
1.47
(–0.01; 0.11)
Vaginal
78 (74.3)
82 (82.0)
1.78d
–
45 (75.0)
33 (78.6)
0.18d
–
C-section
27 (25.7)
18 (18.0)
15 (25.0)
9 (21.4)
Birthweight, mean (g)
3263.5 (661.8)
3341.3 (562.1) 0.91e
–
3403.8 (641.9)c 3640.6 (484.6)c –2.02e –
Low birthweight (≤2500 g)
13 (12.4)
7 (7.0)
1.30
(–0.03; 0.13)
4 (6.7)
Very low birthweight (<1500 g)
3 (2.9)
P-value
Type of delivery:
1 (2.4)
0.99
(–0.04; 0.12)
1 (1.0)
0.96
(–0.02; 0.06) 2 (3.3)
0
1.19
(–0.01; 0.08)
Small for gestational age (birthweight < p10) 7 (6.7)
2 (2.0)
1.63
(–0.01; 0.10)
1 (1.7)
1 (2.4)
–0.26
(–0.06; 0.05)
Large for gestational age (birthweight > p90) 1 (0.9)
4 (4.0)
–1.41
(–0.07; 0.01)
3 (5.0)
2 (4.8)
0.06
(–0.08; 0.09)
0.05b
Data presented as n (%) unless otherwise stated. a Hypertension
pregnancy disorders; gestational diabetes; PPROM; second/third trimester haemorrhage; intrahepatic cholestasis of pregnancy; preterm birth risk; oligohy-
dramnios; fetal growth restriction; thromboembolism OHSS related. b Statistically c If
significant differences. All other P-values are non-significant.
the second child delivery is excluded, mean birthweight: antagonist group (n = 51) 3369.7 (672.4); agonist group (n = 32) 3580.7 (509.4), P = 0.13.
d Chi-squared
test of independence (χ2).
e Independent
samples t-test.GnRH = gonadotrophin-releasing hormone.
Magnusson et al. (2018) using Swedish national data showed no association between the number of oocytes retrieved and any of the poorer perinatal outcomes, but this may be explained by the fact that ovarian stimulation in Sweden is milder and that very few cases were registered with more than 20 oocytes. In this study the agonist protocol resulted in 1.5 more aspirated oocytes than the antagonist protocol, although pregnancy and even cumulative live birth rates were similar with the two protocols (Toftager et al., 2016, 2017). Further, oestradiol levels were 30% higher in the agonist protocol. Hence, this study indicates that differences in oestradiol responses in the two protocols are not associated with changes in perinatal outcomes, but this may be due to the sample size, which was not powered to compare perinatal outcomes. Another difference between the antagonist and agonist protocols is the shedding of the endometrium, which is often more complete in the long agonist
protocol where hypoestrogenism is present for several days before start of stimulation. This is similar to the natural cycle, where oestradiol only starts to rise at the time of the dominance of one follicle after Day 8. The conclusion from the present study is that such factors are unlikely to change the early placentation as the perinatal outcomes were very similar. It is known that a second child has higher birthweight than the first-born, also after ART treatment (Henningsen et al., 2011; Luke et al. 2017b). In the present study, including only children born after FET there was a small but significant higher mean birthweight of children born after the long GnRH agonist protocol. However, this study included one complete ART cycle, thus both the first and the second child from the original stimulation and oocyte retrieval. In the sensitivity analyses on the FET children, where all the second-born children were excluded, no difference was found in mean birthweight between the antagonist and agonist protocols, indicating that the difference in mean birthweight in the FET
children was due to more second-born children after the agonist protocol. Possible differences in perinatal outcomes comparing the two protocols have not been analysed apart from the large Belgian study from 2010, primarily investigating the safety of the new antagonist protocols. In that study, pregnancy and perinatal outcomes after antagonist treatment were prospectively collected and compared with the outcome of a historical control group treated with a GnRH agonist long protocol. It revealed that in terms of obstetrical and neonatal outcomes, treatment with the GnRH antagonist during IVF/ICSI cycles were comparable to GnRH agonists (Bonduelle et al., 2010), which is consistent with the findings of this study. This is the first RCT exploring pregnancy and perinatal outcomes in the GnRH antagonist and agonist protocols. The risk of bias and residual confounding is very low due to the randomized design, with similar background characteristics in the two groups. The mean number of
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embryos transferred and the very low proportion of twins was similar in the two groups, thus twins were excluded in the analyses on perinatal outcomes as the groups were too small to make any twin comparisons meaningful. As perinatal outcomes were secondary outcomes the power calculation was not based on these outcomes. In conclusion, the choice of the GnRH analogue for ART treatments should be based solely on optimizing clinical and safety aspects of the ovarian stimulation per se, as perinatal outcomes are similar in the two protocols.
ACKNOWLEDGEMENTS The authors wish to thank the ReproUnion Committee for supporting the ReproUnion/ESRHE Fellowship programme. We also thank MSD for supporting the study and Gedeon Richter for supporting with some expenses of the first author during the ReproUnion/ESRHE Fellowship programme. An EU/Interreg grant from the ReproUnion consortium and ESHRE fully funded a 6-month fellowship for Claudia Tomás. An unrestricted research grant was provided for the RCT by MSD. The funders had no influence on the data collection, analyses or conclusions of the study.
REFERENCES Berntsen, S., Söderström-Anttila, V., Wennerholm, U.B., Laivuori, H., Loft, A., Oldereid, N.B., Romundstad, L.B., Bergh, C., Pinborg, A. The health of children conceived by ART: ‘the chicken or the egg?’ Hum Reprod Update 2019 Mar 1; 25: 137–158 Bonduelle, M., Oberye, J., Mannaerts, B., Devroey, P. Large prospective, pregnancy and infant follow-up trial assures the health of 1000 fetuses conceived after treatment with the GnRH antagonist ganirelix during controlled ovarian stimulation. Human Reproduction 2010; 25: 1433–1440 Henningsen, A.-K.A., Pinborg, A., Lidegaard, Ø., Vestergaard, C., Forman, J.L., Nyboe Andersen, A. Perinatal outcome of singleton siblings born after assisted reproductive technology and spontaneous conception: Danish national sibling-cohort study. Fertility and Sterility March 1, 2011; 95 Henningsen, A.-K.A., Pinborg, A. Birth and perinatal outcomes and complications for babies conceived following assisted reproductive techniques. Seminars in Fetal and Neonatal Medicine 2014 Imudia, A.N., Awonuga, A.O., Doyle, J.O., Kaimal, A.J., Wright, D.L., Toth, T.L., Styer, A.K. Peak serum oestradiol level during controlled ovarian hyperstimulation is associated with increased risk of small for gestational age and preeclampsia in singleton pregnancies after in vitro fertilization. Fertil. Steril. 2012; 97: 1374–1379 Kamath, M.S., Kirubakaran, R., Mascarenhas, M., Sunkara, S.K. Perinatal outcomes after stimulated versus natural cycle IVF: a systematic review and meta-analysis. Reprod. Biomed. Online 2018 Jan; 36: 94–101 Luke, B., Brown, M.B., Wantman, E., Stern, J.E. Increased risk of large-for-gestational age birthweight in singleton siblings conceived with in vitro fertilization in frozen versus fresh cycles. J. Assist. Reprod. Genet. 2017a; 34: 191–200 Luke, B., Gopal, D., Cabral, H., Stern, J.E., Diop, H. Pregnancy, birth, and infant outcomes by maternal fertility status: the Massachusetts Outcomes Study of Assisted Reproductive Technology. Am. J. Obstet. Gynecol. 2017b; 217: 327.e1–327.e14 Magnusson, Å., Wennerholm, U.B., Källén, K., Petzold, M., Thurin-Kjellberg, A., Bergh, C. The association between the number of oocytes retrieved for IVF, perinatal outcome and obstetric complications. Human Reproduction 2018: 1–9 Marsál, K., Persson, P.H., Larsen, T., Lilja, H., Selbing, A., Sultan, B. Intrauterine growth curves based on ultrasonically estimated fetal weights. Acta Paediatr 1996 Jul; 85: 843–848
Ozgur, K., Berkkanoglu, M., Bulut, H., Humaidan, P., Coetzee, K. Perinatal outcomes after fresh versus vitrified-warmed blastocyst transfer: retrospective analysis. Fertil. Steril. 2015 Oct; 104: 899–907 Pereira, N., Elias, R.T., Christos, P.J., Petrini, A.C., Hancock, K., Lekovich, J.P., Rosenwaks, Z. Supraphysiologic estradiol is an independent predictor of low birth weight in full-term singletons born after fresh embryo transfer. Hum. Reprod. 2017; XX: 1–8 Pinborg, A., Wennerholm, U.B., Romundstad, L.B., Loft, A., Aittomaki, K., Soderstrom-Anttila, V., Nygren, K.G., Hazekamp, J., Bergh, C. Why do singletons conceived after assisted reproduction technology have adverse perinatal outcome? Systematic review and meta-analysis. Hum. Reprod. Update 2013; 19: 87–104 Toftager, M., Bogstad, J., Bryndorf, T., Lossl, K., Roskaer, J., Holland, T., Praetorius, L., Zedeler, A., Nilas, L., Pinborg, A. Risk of severe ovarian hyperstimulation syndrome in GnRH antagonist versus GnRH agonist protocol: RCT including 1050 first IVF/ICSI cycles. Hum. Reprod. 2016; 31: 1253–1264 Toftager, M., Bogstad, J., Løssl, K., Prætorius, L., Zedeler, A., Bryndorf, T., Nilas, L., Pinborg, A. Cumulative live birth rates after one art cycle including all subsequent frozen–thaw cycles in 1050 women: secondary outcome of an RCT. Comparing GnRH-antagonist and GnRHagonist protocols. Human reproduction 2017; 32: 556–567 Romundstad, L.B., Romundstad, P.R., Sunde, A., von During, V., Skjaerven, R., Gunnell, D., Vatten, L.J. Effects of technology or maternal factors on perinatal outcome after assisted fertilization: a population-based cohort study. Lancet 2008; 372: 737–743 Sunkara, S.K., La Marca, A., Seed, P.T., Khalaf, Y. Increased risk of preterm birth and low birthweight with very high number of oocytes following IVF: an analysis of 65 868 singleton live birth outcomes. Human Reproduction 2015; 30: 1473–1480 Sunkara, S.K., LaMarca, A., Polyzos, N.P., Seed, P.T., Khalaf, Y. Live birth and perinatal outcomes following stimulated and unstimulated IVF: analysis of over two decades of a nationwide data. Hum. Reprod. 2016 Oct; 31: 2261–2267 Xiao, J.S., Su, C.M., Zeng, X.T. Comparisons of GnRH Antagonist versus GnRH Agonist Protocol in Supposed Normal Ovarian Responders Undergoing IVF: A Systematic Review and Meta-Analysis. PLoS One 2014 Sep 12; 9e106854 Received 3 April 2019; received in revised form 5 May 2019; accepted 14 May 2019.
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ARTICLE
Perinatal outcomes in 521 gestations after fresh and frozen cycles: a secondary outcome of a randomized controlled trial comparing GnRH antagonist versus GnRH agonist protocols BIOGRAPHY
Dr Claudia Tomás has been a Fertility Consultant at the Fertility Center of Assisted Reproduction, Hospital Garcia de Orta, Portugal since 2017, and currently in the ReproUnion/ESHRE Fellowship programme in the Fertility Clinic, Copenhagen University Hospital, Denmark. Her areas of research activity include perinatal outcomes, reproductive endocrinology and fertility preservation. Claudia Tomás1,3,*, Mette Toftager1, Kristine Løssl1, Jeanette Bogstad1, Lisbeth Prætorius2, Anne Zedeler2, Thue Bryndorf2, Anders Nyboe Andersen1, Anja Pinborg1 KEY MESSAGE
Perinatal outcomes are similar after the GnRH antagonist versus GnRH agonist protocols for ART treatments. The choice of the GnRH analogue should be based solely on optimizing clinical and safety aspects of the ovarian stimulation per se, as perinatal outcomes are similar in the two protocols. ABSTRACT
Research question: Are perinatal outcomes different after treatment with the gonadotrophin-releasing hormone (GnRH) antagonist versus the long GnRH agonist protocol for IVF? Design: Perinatal outcomes were secondary outcomes in a large Phase IV, dual-centre, open-label, randomized controlled trial to compare GnRH antagonist and long GnRH agonist protocols in women <40 years undergoing their first assisted reproductive technology treatment. Women (n = 1050) were randomized in a ratio 1:1 from January 2009 to December 2013 and followed until December 2016. All fresh and frozen embryo transfer (FET) cycles from a single oocyte aspiration, resulting in a gestation (human chorionic gonadotrophin >10 IU/l) were included (n = 521). Data were analysed to compare preterm birth [PTB] (<37 weeks), very PTB (<32 weeks), low birthweight [LBW] (<2500 g) and very LBW (<1500 g) rates among singleton live births in GnRH antagonist versus agonist protocol. Results: Similar perinatal outcomes were found after both protocols. In singletons after fresh embryo transfer, mean gestational age at delivery was 39.1 ± 2.49 versus 39.3 ± 1.90 (P = 0.67) and very PTB rates 1.9% versus 0% (P = 0.17). Mean birthweight was 3264 ± 662 g in the antagonist and 3341 ± 562 g in the agonist group (P = 0.37). LBW was found in 12.4% versus 7% (P = 0.19) and very LBW in 2.9% versus 1% (P = 0.34). In FET cycles, the perinatal outcomes were similar. Small for gestational age and large for gestational age rates were similar in both protocols for singleton live births after fresh and FET. Conclusions: Perinatal outcomes are similar after the GnRH antagonist versus GnRH agonist protocols for IVF. The choice of the GnRH analogue in ovarian stimulation should be based solely on optimizing the chance of pregnancy and not on risks in perinatal outcomes. 1 The
Fertility Clinic, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark of Obstetrics and Gynaecology, Fertility Clinic, Copenhagen University Hospital Hvidovre, Denmark of Infertility and Medically Assisted Reproduction, Hospital Garcia de Orta, Almada, Portugal
2 Department 3 Centre
© 2019 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved. *Corresponding author. E-mail address: [email protected] (C Tomás). https://doi.org/10.1016/j.rbmo.2019.05.010 1472-6483/© 2019 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved. Declaration: The authors report no financial or commercial conflicts of interest.
KEYWORDS
ART GnRH agonist GnRH antagonist Perinatal outcomes
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INTRODUCTION
MATERIALS AND METHODS
he goal of assisted reproductive technology (ART) is to achieve a healthy live-born child, with as few complications as possible during treatment, pregnancy and delivery. However, several studies have shown ART pregnancies to be associated with a higher risk of perinatal complications compared with naturally conceived pregnancies (Sunkara et al., 2016) and also, women undergoing ART treatment are on average older and have various comorbidities before conception (Henningsen and Pinborg, 2014).
Study design Pregnancy and perinatal outcome were secondary outcomes in a large Phase IV, dual-centre, open-label, randomized controlled trial (RCT), with the objective to compare the GnRH antagonist and the long GnRH agonist protocols in an unselected population referred for their first ART treatment. Women (n = 1050) were randomized in a ratio of 1:1 over a period of 5 years from January 2009 to December 2013 and were followed for 3–8 years, until December 2016. Study design including inclusion and exclusion criteria are described in two previous publications (Toftager et al., 2016, 2017).
T
Evidence shows that children born after ART treatment have an increased risk of adverse perinatal outcomes such as preterm birth (PTB), low birthweight (LBW), small for gestational age (SGA) and large for gestational age (LGA) (Henningsen and Pinborg, 2014; Kamath MS et al., 2018; Sunkara et al., 2016). Different perinatal risk profiles are associated with different ART treatments, frozen embryo transfer (FET) being associated with a higher risk of singletons being LGA and macrosomic (Henningsen and Pinborg, 2014). Poor perinatal outcomes are known to be associated not only with increased neonatal morbidity but also with long-term health outcomes, including an increased risk of diseases related to metabolic syndrome (Ozgur et al., 2015). The widespread use of elective single embryo transfer (eSET) has considerably improved perinatal and obstetric outcomes in ART treatment; however, singleton pregnancies after ART treatment still carry an increased risk of perinatal complications (Luke et al., 2017a). One additional factor that may influence the outcome of pregnancies is the ovarian stimulation protocol. It is known that the GnRH antagonist protocol and GnRH agonist protocol differ regarding number of oocytes retrieved, oestradiol peak levels and ovarian hyperstimulation syndrome (OHSS) risks, besides similar live birth rates (Toftager et al., 2016; Xiao et al., 2014). Hence these two different ovarian stimulation regimens may also result in different perinatal outcomes. The aim of this study was to explore perinatal outcomes in gestations following the GnRH antagonist versus the agonist cycle.
Participants All fresh and FET cycles leading to a gestation, human chorionic gonadotrophin (HCG) >10 IU/l (13–15 days after transfer) were included (n = 521). All women were under 40 years of age and referred for their first ART treatment cycle at two public fertility clinics in Denmark: Hvidovre Hospital, Copenhagen and Dronninglund Hospital, Aalborg. All women underwent one complete ART cycle including fresh and subsequent frozen–thawed embryo transfers. FIGURE 1 provides a chart of all included pregnancies; in total there were 347 gestations with positive HCG after fresh transfer, 174 gestations after FET, 225 ongoing pregnancies after fresh and 115 after FET (FIGURE 1). Outcome measures Positive HCG and ongoing pregnancy were registered at visits to the fertility clinic and documented in the electronic case report form. Perinatal outcomes were based on a maternal self-reported questionnaire posted to the mother after delivery and returned to the fertility clinic. Additional information was obtained from the medical birth files. A miscarriage was defined as the spontaneous loss of a pregnancy before gestational age 22 + 0. A stillbirth was the delivery of a deceased infant after 22 + 0 weeks of gestation. A live birth, defined as both singleton and twin births, was the delivery of a live-born child after 22 + 0 weeks. PTB was defined as a live birth at <37 + 0 weeks of gestation and very preterm birth (VPTB) as a live birth <32 + 0 weeks of gestation. LBW was a live infant delivered with a weight of <2500 g, and very LBW (VLBW) was
a live infant delivered with a weight of <1500 g. The classic definition for SGA and LGA is a fetal birthweight less than or equal to the 10th and more than or equal to the 90th percentile for a given gestational age, respectively (Marsál et al., 1996). Statistical methods Only cycles resulting in a gestation (HCG >10 IU/l) after fresh embryo transfer and/or FET were included in this study. Data are presented as mean and SD for continuous variables and compared with Student's t-test. For proportions the chi-squared test was used (or the likelihood ratio test if the former was not possible). To avoid the bias of twins, only singletons were compared regarding perinatal outcomes. A P-value <0.05 was considered statistically significant. Data were analysed using SPSS Statistics for Windows, Version 23 (IBM Corp., Armonk, NY, USA). Ethics The RCT study was approved by the Danish Scientific Ethics Committee, Capital Region of Denmark, Protocol #: H-B-2008-109, and approved by the Danish Medicines Agency, EudraCT #: 2008-005452-24. Registration ID on ClinicalTrials.gov: NCT00756028. The study is reported according to the CONSORT statements. All subjects provided written informed consent.
RESULTS As shown in TABLE 1, women that were pregnant after fresh embryo transfer had comparable baseline characteristics and demographic parameters in terms of age, body mass index (BMI), smoking status, previous pregnancy or delivery, duration of infertility and the distribution of primary cause of infertility, between the GnRH antagonist and GnRH agonist groups (NS). Severe OHSS (grades 4 and 5) occurred in 7.7% versus 13.3% in the antagonist versus the agonist group, respectively. The endometrial preparation before FET was performed with a natural modified cycle in 81.6% of the antagonist versus 80.3% of the agonist cycles or with an artificial cycle in 18.4% versus 18.4% (P = 0.99). The mean number of frozen embryos transferred was 1.55 ± 0.50 in both antagonist and agonist protocols. shows pregnancy and delivery outcomes after antagonist and agonist TABLE 2
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FIGURE 1 Flow chart of overview of the outcomes (ET = embryo transfer; FET = frozen embryo transfer; GnRH = gonadotrophin-releasing
hormone).
TABLE 1 BASELINE CHARACTERISTICS AND CYCLE RESULTS OF PREGNANT WOMEN AFTER FRESH EMBRYO TRANSFER GnRH antagonist group (n = 181)
GnRH agonist group (n = 166)
Age at inclusion, mean (SD)
32.0 (4.2)
32.0 (4.1)
BMI (kg/m²), mean (SD)
24.7 (4.1)
24.4 (4.0)
Non-smoker
169 (93.4)
154 (92.8)
Actual smoker
12 (6.6)
12 (7.2)
Previous pregnancya
57 (31.5)
44 (26.5)
13 (7.2)
9 (5.4)
Male
80 (44.2)
81 (48.8)
Female
37 (20.4)
36 (21.7)
Unexplained
50 (27.6)
42 (25.3)
Other causes
14 (7.7)
7 (4.2)
Duration of infertility (years), mean (SD)
2.3 (1.7)
2.5 (1.7)
ICSI
60 (33.1)
61 (36.7)
IVF
121 (66.9)
105 (63.3)
Oestradiol level on the day of HCG (nmol/ml), mean (SD)
3.1 (2.3)
4.3 (2.4)
Number of fresh transferred embryos, mean (SD)
1.2 (0.4)
1.2 (0.4)
Number of frozen embryos, median
1
2
Severe OHSS (grades 4 and 5)
14 (7.7)
22 (13.3)
Smoking status:
Previous
deliverya
Primary cause of infertility:
Intended IVF method:
Data are presented as n (%) unless otherwise stated. a Including
spontaneous and fertility treatments other than IVF/ICSI. There were no statistically significant differences between the two groups.
BMI = body mass index; GnRH = gonadotrophin-releasing hormone; HCG = human chorionic gonadotrophin; ICSI = intracytoplasmic sperm injection; OHSS = ovarian hyperstimulation syndrome.
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TABLE 2 PREGNANCY OUTCOMES AFTER FRESH AND FROZEN EMBRYO TRANSFER IN EITHER GNRH ANTAGONIST OR AGONIST PROTOCOL WITH STRATIFICATION BY FRESH AND FROZEN EMBRYO TRANSFER Fresh embryo transfer
Frozen embryo transfer
GnRH antagonist group (n = 181)
GnRH agonist group (n = 166)
Z
95% CI
GnRH antagonist group (n = 98)
GnRH agonist group (n = 76)
Z
95% CI
Early (<12 weeks)
58 (32.0)
57 (34.3)
–0.34
(–0.12; 0.08)
29 (29.6)
24 (31.6)
–0.28
(–0.16; 0.12)
Late (>12 weeks)
4
(2.2)a
2 (1.2)
0.72
(–0.02; 0.04)
0
2 (2.6)
–1.62
(–0.06; 0.01)
Ectopic pregnancy
1 (0.6)
0
0.96
(–0.01; 0.02)
2 (2.0)
2 (2.6)
–0.26
(–0.05; 0.04)
Ongoing pregnancy >22 weeks
118 (65.2)
107 (64.5)
0.14
(–0.09; 0.11)
67 (68.4)b
48 (63.2)b
0.72
(–0.09; 0.19)
Singleton pregnancy
105 (58.0)
100 (60.2)
–0.42
(–0.13; 0.08)
60 (61.2)
42 (55.3)
0.79
(–0.09; 0.21)
Twin pregnancy
11 (6.1)
6 (3.6)
1.06
(–0.02; 0.07)
6 (6.1)
4 (5.3)
0.24
(–0.06; 0.08)
Live birth
116 (64.1)
106 (63.9)
0.05
(–0.10; 0.10)
66 (67.3)
46 (60.5)
0.93
(–0.08; 0.21)
Stillbirth (>22 weeks)
2 (1.1)
1 (0.6)
0.50
(–0.01; 0.02)
0
0
–
–
Miscarriage:
c
All P-values are non-significant (P > 0.05). Data presented as n (%) unless otherwise stated. a One
late miscarriage for medical interruption of pregnancy for trisomy 21.
b Three c Twins
cases lost in follow-up in frozen embryo transfer (one in the antagonist group, two in the agonist group). counts as one live birth.
CI = confidence interval; GnRH = gonadotrophin-releasing hormone.
protocols stratified after fresh and FET. No statistical differences were observed in pregnancy outcomes between the GnRH antagonist and agonist cycles either in fresh or in FET pregnancies. Only three cases of ongoing pregnancy were lost to follow-up. Perinatal outcomes are depicted in TABLE 3 . The gestational age at delivery after fresh embryo transfer was 39.1 ± 2.5 and 39.3 ± 1.9 weeks in the antagonist versus the agonist group (P = 0.67). Among the PTB (9.5% versus 10%; P = 0.91), the majority had a late PTB. Only 1.9% and 0% (P = 0.17) had a VPTB in the antagonist versus the agonist group. The mean birthweight of singleton live births after fresh embryo transfer was 3263.5 ± 661.8 g in the antagonist group and 3341.3 ± 562.1 g in the agonist group (P = 0.37); 12.4% versus 7% (P = 0.19) had a LBW, and 2.9% versus 1% (P = 0.34) a VLBW. According to Marsál standard curves, SGA was found in 6.7% versus 2% (P = 0.10) and LGA in 0.95% versus 4% (P = 0.16) in the GnRH antagonist versus GnRH agonist protocols, respectively. In pregnancies after FET similar results were found except that the mean birthweight was 3403.8 ± 641.9 g versus 3640.6 ± 484.6 g and P < 0.05 in the antagonist and agonist groups, respectively. However, if the second child delivery after a FET was excluded (9 in the antagonist protocol and 10
in the agonist protocol), the mean birthweight in the antagonist and agonist protocols were similar (3369.7 ± 672.4 g versus 3580.7 ± 509.4 g, P = 0.13). No differences were found in either SGA or LGA rates between the protocols. Obstetric complications were registered in very few cases and no differences were observed either in fresh or FET (TABLE 3). No neonatal deaths or congenital malformations were reported among singletons.
DISCUSSION No differences were observed in perinatal outcomes after GnRH antagonist versus GnRH agonist when viewing complete ART treatment cycles. The clinical consequence is that the choice of protocol for ovarian stimulation should not be determined by perinatal concerns, but solely on optimizing the balance between chance of pregnancy and risk of OHSS. Many factors affect pregnancy and perinatal outcomes, both directly and indirectly, and the causes of the poorer perinatal outcomes following IVF are most probably multifactorial (Berntsen et al., 2019). Both subfertility per se and IVF treatment, including ovarian stimulation and embryo culture techniques, have been suggested as risk factors for adverse perinatal and
obstetric outcomes (Magnusson et al., 2018; Pinborg et al., 2013). The antagonist and the long agonist protocols differ in several respects. The total gonadotrophin doses used are higher, the length of stimulation longer, pre-trigger oestradiol levels higher, number of aspirated oocytes higher, and the risk of OHSS is increased with the GnRH agonist protocol. Based on data from sibling studies, comparing children born after fresh and frozen cycles, it is known that the birthweight is lower after ovarian stimulation (Henningsen et al., 2011; Romundstad et al., 2008). All factors that can cause changes in the oocyte and endometrium lead to epigenetic changes in early embryo development and implantation and may change pregnancy and perinatal outcomes (Pinborg et al., 2013). Pereira et al. 2017 showed that supraphysiologic oestradiol was an independent predictor of LBW in full-term singletons born after fresh embryo transfer. In fresh cycles, the elevated oestradiol level on the day of the trigger is closely related also to SGA and pre-eclampsia due to abnormal early placentation (Imudia et al., 2012). Consistent with these findings, Sunkara et al. (2015) showed, based on the national UK data from the Human Fertilisation and Embryology Authority, that women with more than 20 aspirated oocytes have a higher risk of PTB and LBW. In contrast, the study by
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TABLE 3 PERINATAL OUTCOMES IN SINGLETONS AFTER BOTH FRESH AND FROZEN EMBRYO TRANSFER IN EITHER GNRH ANTAGONIST OR AGONIST PROTOCOL WITH STRATIFICATION BY FRESH AND FROZEN EMBRYO TRANSFER Fresh embryo transfer
Frozen embryo transfer
GnRH antagonist group (n = 105)
GnRH agonist group (n = 100)
Z
95% CI
GnRH antagonist group (n = 60)
GnRH agonist group (n = 42)
Z
95% CI
Complications during pregnancya
15 (14.3)
16 (16.0)
–0.34
(–0.12; 0.08)
8 (13.3)
3 (7.1)
0.99
(–0.05; 0.18)
Gestational age at delivery, mean (SD)
39.1 (2.5)
39.3 (1.9)
–0.43e –
39.3 (3.0)
39.7 (1.5)
–0.74e –
Induction of labour
22 (21.0)
24 (24.0)
–0.52
(–0.15; 0.08)
14 (23.3)
13 (31.0)
–0.86
(–0.25; 0.10)
Term delivery
95 (90.5)
90 (90.0)
0.12
(–0.08; 0.09)
53 (88.3)
39 (92.9)
–0.76
(–0.16; 0.07)
Preterm birth (<37 weeks)
10 (9.5)
10 (10.0)
–0.16
(–0.09; 0.08)
7 (11.7)
3 (7.1)
0.76
(–0.07; 0.16)
Very preterm birth (<32 weeks)
2 (1.9)
0
1.39
(–0.01; 0.05) 3 (5.0)
0
1.47
(–0.01; 0.11)
Vaginal
78 (74.3)
82 (82.0)
1.78d
–
45 (75.0)
33 (78.6)
0.18d
–
C-section
27 (25.7)
18 (18.0)
15 (25.0)
9 (21.4)
Birthweight, mean (g)
3263.5 (661.8)
3341.3 (562.1) 0.91e
–
3403.8 (641.9)c 3640.6 (484.6)c –2.02e –
Low birthweight (≤2500 g)
13 (12.4)
7 (7.0)
1.30
(–0.03; 0.13)
4 (6.7)
Very low birthweight (<1500 g)
3 (2.9)
P-value
Type of delivery:
1 (2.4)
0.99
(–0.04; 0.12)
1 (1.0)
0.96
(–0.02; 0.06) 2 (3.3)
0
1.19
(–0.01; 0.08)
Small for gestational age (birthweight < p10) 7 (6.7)
2 (2.0)
1.63
(–0.01; 0.10)
1 (1.7)
1 (2.4)
–0.26
(–0.06; 0.05)
Large for gestational age (birthweight > p90) 1 (0.9)
4 (4.0)
–1.41
(–0.07; 0.01)
3 (5.0)
2 (4.8)
0.06
(–0.08; 0.09)
0.05b
Data presented as n (%) unless otherwise stated. a Hypertension
pregnancy disorders; gestational diabetes; PPROM; second/third trimester haemorrhage; intrahepatic cholestasis of pregnancy; preterm birth risk; oligohy-
dramnios; fetal growth restriction; thromboembolism OHSS related. b Statistically c If
significant differences. All other P-values are non-significant.
the second child delivery is excluded, mean birthweight: antagonist group (n = 51) 3369.7 (672.4); agonist group (n = 32) 3580.7 (509.4), P = 0.13.
d Chi-squared
test of independence (χ2).
e Independent
samples t-test.GnRH = gonadotrophin-releasing hormone.
Magnusson et al. (2018) using Swedish national data showed no association between the number of oocytes retrieved and any of the poorer perinatal outcomes, but this may be explained by the fact that ovarian stimulation in Sweden is milder and that very few cases were registered with more than 20 oocytes. In this study the agonist protocol resulted in 1.5 more aspirated oocytes than the antagonist protocol, although pregnancy and even cumulative live birth rates were similar with the two protocols (Toftager et al., 2016, 2017). Further, oestradiol levels were 30% higher in the agonist protocol. Hence, this study indicates that differences in oestradiol responses in the two protocols are not associated with changes in perinatal outcomes, but this may be due to the sample size, which was not powered to compare perinatal outcomes. Another difference between the antagonist and agonist protocols is the shedding of the endometrium, which is often more complete in the long agonist
protocol where hypoestrogenism is present for several days before start of stimulation. This is similar to the natural cycle, where oestradiol only starts to rise at the time of the dominance of one follicle after Day 8. The conclusion from the present study is that such factors are unlikely to change the early placentation as the perinatal outcomes were very similar. It is known that a second child has higher birthweight than the first-born, also after ART treatment (Henningsen et al., 2011; Luke et al. 2017b). In the present study, including only children born after FET there was a small but significant higher mean birthweight of children born after the long GnRH agonist protocol. However, this study included one complete ART cycle, thus both the first and the second child from the original stimulation and oocyte retrieval. In the sensitivity analyses on the FET children, where all the second-born children were excluded, no difference was found in mean birthweight between the antagonist and agonist protocols, indicating that the difference in mean birthweight in the FET
children was due to more second-born children after the agonist protocol. Possible differences in perinatal outcomes comparing the two protocols have not been analysed apart from the large Belgian study from 2010, primarily investigating the safety of the new antagonist protocols. In that study, pregnancy and perinatal outcomes after antagonist treatment were prospectively collected and compared with the outcome of a historical control group treated with a GnRH agonist long protocol. It revealed that in terms of obstetrical and neonatal outcomes, treatment with the GnRH antagonist during IVF/ICSI cycles were comparable to GnRH agonists (Bonduelle et al., 2010), which is consistent with the findings of this study. This is the first RCT exploring pregnancy and perinatal outcomes in the GnRH antagonist and agonist protocols. The risk of bias and residual confounding is very low due to the randomized design, with similar background characteristics in the two groups. The mean number of
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embryos transferred and the very low proportion of twins was similar in the two groups, thus twins were excluded in the analyses on perinatal outcomes as the groups were too small to make any twin comparisons meaningful. As perinatal outcomes were secondary outcomes the power calculation was not based on these outcomes. In conclusion, the choice of the GnRH analogue for ART treatments should be based solely on optimizing clinical and safety aspects of the ovarian stimulation per se, as perinatal outcomes are similar in the two protocols.
ACKNOWLEDGEMENTS The authors wish to thank the ReproUnion Committee for supporting the ReproUnion/ESRHE Fellowship programme. We also thank MSD for supporting the study and Gedeon Richter for supporting with some expenses of the first author during the ReproUnion/ESRHE Fellowship programme. An EU/Interreg grant from the ReproUnion consortium and ESHRE fully funded a 6-month fellowship for Claudia Tomás. An unrestricted research grant was provided for the RCT by MSD. The funders had no influence on the data collection, analyses or conclusions of the study.
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