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Does cesarean section pose a risk of respiratory syncytial virus bronchiolitis in infants and children?
S134
Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
Contents lists available at ScienceDirect
Asian Pacific Journal of Tropical Medicine journal homepage:www.elsevier.com/locate/apjtm
Document heading
doi: 10.1016/S1995-7645(14)60219-4
D oes
cesarean section pose a risk of respiratory syncytial virus bronchiolitis in infants and children? 1*
Mohamed A. Hendaus
, Ahmed H. Alhammadi1,2, Mohamed S. Khalifa1, Eshan Muneer1
Department of Pediatrics, General Pediatrics Section, Hamad Medical Corporation, Doha, Qatar
1
Weil Cornell Medical College, Doha, Qatar
2
ARTICLE INFO
ABSTRACT
Article history: Received 7 Jul 2014 Received in revised form 14 Jul 2014 Accepted 28 Jul 2014 Available online 7 Aug 2014
Objective: To determine the risk of acquiring acute respiratory syncytial virus (RSV) bronchiolitis in infants and children delivered by the mode of cesarean section (C-section). Methods: A retrospective and descriptive study was conducted at Hamad Medical Corporation. Patients with ages 0 to 36 months hospitalized with acute bronchiolitis were included in the study. Results: The risk of RSV bronchiolitis was observed to be higher among C-section delivery compared to normal spontaneous vaginal delivery [odds ratio=1.10; 95% confidence interval (0.57, 1.80); P=0.965]; however, it was not statistically significant. Gestational age ≤35 weeks was significantly associated with increased risk of RSV bronchiolitis compared to gestational age >35 weeks [odds ratio=3.12; 95% confidence interval (1.53, 6.38); P=0.002]. Conclusions: Delivery by C-section does not appear to increase the risk of RSV bronchiolitis in infants compared with normal spontaneous vaginal delivery.
Keywords: Bronchiolitis Mode Delivery
1. Introduction Acute lower respiratory infections constitute a large proportion of hospitalization in young children[1]. Viral bronchiolitis comprises 19% of total pediatric hospital admissions in the United States[2]. Cesarean sections (C-sections) have been considered as a global burden for many years; the rate of cesarean procedures has been on the rise and it has reached to 64 . 1 % in some areas in C hina [3]. E lective C -section is reported to increase postpartum depression[4], maternal morbidity and mortality, neonatal death, and neonatal admission to the neonatal intensive care unit, not to mention the financial burden on families and on the health care system[3]. Some studies reported association between cesarean *Corresponding author: Mohamed A. Hendaus, MD, FAAP, Department of Pediatrics, General Pediatrics Section, Hamad Medical Corporation, Doha, Qatar. Tel: +974-4439-2239 Fax: +974-4443-9571 E-mail: [email protected] Foundation Project: Supported by Hamad Medical Corporation (Ref #.13139/13).
delivery and newborn serious respiratory morbidity [5], respiratory distress [6] , transient tachypnea of the newborn[7], birth trauma[8], child obesity[9], and decrease rate of breastfeeding[10]. The aim of this study was to analyze the risk of acquiring respiratory syncytial virus (RSV) bronchiolitis in children delivered via the mode of C-section. 2. Materials and methods Our study was descriptive and retrospective and was administered at Hamad Medical Corporation, the only tertiary center in Qatar. Infants and children ages 0 to 36 months hospitalized with acute bronchiolitis from January 1, 2010 to December 31, 2012 were included in the study. T he following data were collected: age at diagnosis, gestational age, sex, respiratory virus polymerase chain reaction (RV-PCR) and mode of delivery. The RSV positive group included children admitted for bronchiolitis and RV-PCR was positive for RSV, and the RSV negative group is defined as children with clinical bronchiolitis but the RVPCR was negative.
S135
Mohamed A. Hendaus et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
The diagnosis of bronchiolitis was based on the American Academy of Pediatrics definition[11]. RV - PCR for commonly diagnosed respiratory viruses
was done by obtaining nasal secretions from each patient. Patients with no RV-PCR or no proper documentation of the mode of delivery were excluded. Approval for the study was obtained from Hamad Medical Corporation-Ethics Committee (Ref #13139/13). D escriptive statistics were used to summarize demographic and all other clinical characteristics of the participants. Q uantitative data values were expressed as frequency along with percentage and mean依SD with median and range. The primary outcome variable is odds of acquiring RSV bronchiolitis in children born via C-section with 95% confidence interval (CI). Quantitative variables means between two and more than two independent groups were analyzed using unpaired ‘t’ test and O ne way ANOVA . P air-wise comparisons were made using B onferroni multiple comparison test where an overall group difference was found statistically significant. The results were presented with the associated 95 % CI. I n addition, for non-normal or skewed data, Mann-Whitney U and Kruskal-Wallis tests were applied. Logistic regression analysis results were presented in terms of odds ratio (OR) and associated 95% CI. A two-sided P value <0.05 was considered to be statistically significant. All statistical analyses were done using statistical packages SPSS 19.0 (SPSS Inc., Chicago, IL). 3. Results A total number of 836 pediatric patients with acute bronchiolitis were admitted to the pediatric ward during the study period of January 1, 2010 till December 31, 2012. W e excluded 66 patients because RV - PCR was not performed on them. O f the remaining 770 patients, we had to exclude an additional 92 cases since the mode of delivery was not documented. The mean age at diagnosis was ( 3 . 61 依 3 . 56 ) months ranged from 10 d to 34 months. There were approximately 60% boys and 40% girls. The mean gestational age was (37.01依3.37) weeks ranged from 25 to 42 weeks, and less than 20 % of infants had been delivered with gestational age fewer than 35 weeks. Factors associated with mode of delivery are presented in Table 1. The mean age in the RSV-positive group was (3.43依3.63) months compared to (2.95依2.36) months in the RSV-negative group.
Table 1 Factors associated with mode of delivery.
Factors RV-PCR status
NSVD
Out of the 678 patients, 493 (72.7%) were delivered via the mode of NSVD and 185 via C-section (27.3%). For the NSVD group, RSV was positive in 215 patients (43.6%), RSV negative in 92 (18.7%) and other than RSV in 186 (37.7%). For the C-section group, 89 tested RSV positive (48.1%), 35 RSV negative (18.9%) and 61 were positive for viruses other than RSV (33.0%). The percentage of RSV bronchiolitis was observed to be higher in C-section delivery compared to NSVD (48.1% vs. 43.6%, P=0.485). Furthermore, logistic regression analysis revealed that the risk of RSV bronchiolitis was observed to be higher among C-section delivery compared to NSVD [OR=1.10; 95% CI (0.57, 1.80); P=0.965]. Gestational age ≤35 weeks was significantly associated with increased risk of RSV bronchiolitis compared to gestational age >35 weeks [OR=3.12; 95% CI (1.53, 6.38); P=0.002].
4. Discussion There are few studies in the literature mentioning the risk of cesarean delivery as a risk factor for lower respiratory infections. I n a large cohort study, M oore et al. found that 4.1% of the overall acute lower respiratory infections hospitalization rate was due to delivery by C-section[1]. C esarean delivery might lead to decrease the infant immunity, hence increase the risk of early viral lower respiratory infections[11]. RSV bronchiolitis is considered as one of the main diagnoses for hospitalized infants with a rate of 25 . 2 per 1 000 infants[12], and a main source of morbidity in the outpatient settings[13]. T he risk of RSV mortality is usually higher in infants born premature or with low birth weight[12]. Children under 2 years of age born via the cesarean mode have an increased risk of bronchiolitis with an incidence rate ratio that ranges between 1.11 and 1.20[11]. Our study did not echo the risk; we found that infants born via C-section had no higher risk of acquiring RSV bronchiolitis. I n a large retrospective study that included 1 284 newborns delivered by elective caesarean, Z anardo et al. concluded that respiratory distress syndrome risk was increased in infants born earlier than 38 weeks and 6 days[14]. However, there was no significant risk of respiratory distress syndrome in infants born at 39 weeks and above via cesarean compared to NSVD[15].
RSV positive 215 (43.6%) RSV negative 92 (18.7%) Other than RSV 186 (37.7%) Gender Male 295 (59.8%) Female 198 (40.2%) Age at diagnosis (months) Mean依SD [median (range)] 3.56依3.52 [2.47 (0.33-33)] Gestational age (weeks) Mean依SD [median (range)] 37.84依2.77 [39 (25-42)]
C-section
Total
P-value*
127 (18.7%)
0.485
438 (59.5%)
0.467
3.61依3.56 [3 (0.33-34)]
0.958 <0.001
89 (48.1%)
304 (44.8%)
61 (33.0%)
247 (36.5%)
35 (18.9%) 105 (56.7%) 80 (43.3%)
3.58依3.52 [3 (0.4-34)]
35.36依3.86 [37 (25-42)]
298 (40.5%)
37.01依3.37 [38 (25-42)]
NSVD: Normal spontaneous vaginal delivery; P-value computed using Chi-square, unpaired t test, Mann-Whitney U test. *
S136
Mohamed A. Hendaus et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
Some authors mentioned that children born via cesarean had an increased risk of asthma later in childhood[16-19]. However, other authors do not agree[20-23]. Moreover, Bager et al. reported an increased risk of allergic rhinitis and asthma[24]. Our study as well as the studies referred to in this paper, analyzed the association between RSV bronchiolitis and the mode of delivery. However, it might be merely an association while the pathophysiology is still unknown. O ur limitation could be attributed to the number of patients born by C -section, and almost 100 patients lacked the documentation of their mode of delivery as they were born outside our health care facility. We also have inadequate information about genetic factors, and pregnancy circumstances. Since it was a retrospective study, we did not have full control of all variables and we lacked the information of whether the C-sections were performed electively or on an emergency basis. Our study will open a new scope for larger studies. Delivery by C-section does not appear to increase the risk of RSV bronchiolitis in infants compared with NSVD.
Conflict of interest statement The authors report no conflicts of interest in this work. Acknowledgements W e would like to thank D r. P rem C handra from the Medical Research Center at Hamad Medical Corporation in Qatar, who took time out of his intense schedule to assist in data analysis. Hamad Medical Corporation (Ref #.13139/13) provided US dollars of 6 850.
References [1] Moore HC, de Klerk N, Richmond P, Lehmann D. A retrospective population-based cohort study identifying target areas for prevention of acute lower respiratory infections in children. BMC Public Health 2010; 10: 757. [2] Yorita KL, Holman RC, Sejvar JJ, Steiner CA, Schonberger LB. Infectious disease hospitalizations among infants in the United States. Pediatrics 2008; 121(2): 244-252. [3] Feng XL, Wang Y, An L, Ronsmans C. Cesarean section in the People’s Republic of China: current perspectives. Int J Womens Health 2014; 6: 59-74. [4] Xie RH, Lei J, Wang S, Xie H, Walker M, Wen SW. Cesarean section and postpartum depression in a cohort of Chinese women with a high cesarean delivery rate. J Womens Health (Larchmt) 2011; 20(12): 1881-1886. [5] Hansen AK, Wisborg K, Uldbjerg N, Henriksen TB. Risk of respiratory morbidity in term infants delivered by elective caesarean section: cohort study. BMJ 2008; 336(7635): 85-87. [6] G erten KA , C oonrod DV , B ay RC , C hambliss LR . C esarean
delivery and respiratory distress syndrome: does labor make a difference? Am J Obstet Gynecol 2005; 193(3 Pt 2): 1061-1064. [7] Fogelson NS, Menard MK, Hulsey T, Ebeling M. Neonatal impact of elective repeat cesarean delivery at term: a comment on patient choice cesarean delivery. Am J Obstet Gynecol 2005; 192(5): 14331436. [8] Moczygemba CK, Paramsothy P, Meikle S, Kourtis AP, Barfield WD , K uklina E , et al. R oute of delivery and neonatal birth trauma. Am J Obstet Gynecol 2010; 202(4): 361.e1-e6. [9] Huh SY, Rifas-Shiman SL, Zera CA, Edwards JW, Oken E, Weiss ST, et al. Delivery by caesarean section and risk of obesity in preschool age children: a prospective cohort study. Arch Dis Child 2012; 97(7): 610-616. [10] Liu X, Zhang J, Liu Y, Li Y, Li Z. The association between cesarean delivery on maternal request and method of newborn feeding in China. PLoS One 2012; 7(5): e37336. [11] American Academy of Pediatrics Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics 2006; 118(4): 1774-1793. [12] L eader S , K ohlhase K . R espiratory syncytial virus-coded pediatric hospitalizations, 1997 to 1999. Pediatr Infect Dis J 2002; 21(7): 629-632. [13] Hall CB, Weinberg GA, Iwane MK, Blumkin AK, Edwards KM, Staat MA, et al. The burden of respiratory syncytial virus infection in young children. N Engl J Med 2009; 360(6): 588-598. [14] Z anardo V , S imbi AK , F ranzoi M , S old à G , S alvadori A , Trevisanuto D. Neonatal respiratory morbidity risk and mode of delivery at term: influence of timing of elective caesarean delivery. Acta Paediatr 2004; 93(5): 643-647. [15] M oore HC , de K lerk N , H olt P , R ichmond PC , L ehmann D . Hospitalisation for bronchiolitis in infants is more common after elective caesarean delivery. Arch Dis Child 2012; 97(5): 410-414. [16] Thavagnanam S, Fleming J, Bromley A, Shields MD, Cardwell CR. A meta-analysis of the association between caesarean section and childhood asthma. Clin Exp Allergy 2008; 38: 629-633. [17] Adams M, Doull I. Birth by caesarean section and asthma. Clin Exp Allergy 2008; 38: 554-556. [18] Tollånes MC, Moster D, Daltveit AK, Irgens LM. Cesarean section and risk of severe childhood asthma: a population-based cohort study. J Pediatr 2008; 153: 112-116. [19] Roduit C, Scholtens S, de Jongste JC, Wijga AH, Gerritsen J, Postma DS, et al. Asthma at 8 years of age in children born by caesarean section. Thorax 2009; 64: 107-113. [20] Almqvist C, Cnattingius S, Lichtenstein P, Lundholm C. The impact of birth mode of delivery on childhood asthma and allergic diseases--a sibling study. Clin Exp Allergy 2012; 42(9): 1369-1376. [21] Maitra A, Sherriff A, Strachan D, Henderson J; ALSPAC Study Team. Mode of delivery is not associated with asthma or atopy in childhood. Clin Exp Allergy 2004; 34: 1349-1355. [22] Werner A, Ramlau-Hansen CH, Jeppesen SK, Thulstrup AM, Olsen J. Caesarean delivery and risk of developing asthma in the offspring. Acta Paediatr 2007; 96: 595-596. [23] Menezes AM, Hallal PC, Matijasevich AM, Barros AJ, Horta BL, Araujo CL, et al. Caesarean sections and risk of wheezing in childhood and adolescence: data from two birth cohort studies in Brazil. Clin Exp Allergy 2011; 41: 218-223. [24] Bager P, Wohlfahrt J, Westergaard T. Caesarean delivery and risk of atopy and allergic disease: meta-analyses. Clin Exp Allergy 2008; 38: 634–642.
Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
Contents lists available at ScienceDirect
Asian Pacific Journal of Tropical Medicine journal homepage:www.elsevier.com/locate/apjtm
Document heading
doi: 10.1016/S1995-7645(14)60219-4
D oes
cesarean section pose a risk of respiratory syncytial virus bronchiolitis in infants and children? 1*
Mohamed A. Hendaus
, Ahmed H. Alhammadi1,2, Mohamed S. Khalifa1, Eshan Muneer1
Department of Pediatrics, General Pediatrics Section, Hamad Medical Corporation, Doha, Qatar
1
Weil Cornell Medical College, Doha, Qatar
2
ARTICLE INFO
ABSTRACT
Article history: Received 7 Jul 2014 Received in revised form 14 Jul 2014 Accepted 28 Jul 2014 Available online 7 Aug 2014
Objective: To determine the risk of acquiring acute respiratory syncytial virus (RSV) bronchiolitis in infants and children delivered by the mode of cesarean section (C-section). Methods: A retrospective and descriptive study was conducted at Hamad Medical Corporation. Patients with ages 0 to 36 months hospitalized with acute bronchiolitis were included in the study. Results: The risk of RSV bronchiolitis was observed to be higher among C-section delivery compared to normal spontaneous vaginal delivery [odds ratio=1.10; 95% confidence interval (0.57, 1.80); P=0.965]; however, it was not statistically significant. Gestational age ≤35 weeks was significantly associated with increased risk of RSV bronchiolitis compared to gestational age >35 weeks [odds ratio=3.12; 95% confidence interval (1.53, 6.38); P=0.002]. Conclusions: Delivery by C-section does not appear to increase the risk of RSV bronchiolitis in infants compared with normal spontaneous vaginal delivery.
Keywords: Bronchiolitis Mode Delivery
1. Introduction Acute lower respiratory infections constitute a large proportion of hospitalization in young children[1]. Viral bronchiolitis comprises 19% of total pediatric hospital admissions in the United States[2]. Cesarean sections (C-sections) have been considered as a global burden for many years; the rate of cesarean procedures has been on the rise and it has reached to 64 . 1 % in some areas in C hina [3]. E lective C -section is reported to increase postpartum depression[4], maternal morbidity and mortality, neonatal death, and neonatal admission to the neonatal intensive care unit, not to mention the financial burden on families and on the health care system[3]. Some studies reported association between cesarean *Corresponding author: Mohamed A. Hendaus, MD, FAAP, Department of Pediatrics, General Pediatrics Section, Hamad Medical Corporation, Doha, Qatar. Tel: +974-4439-2239 Fax: +974-4443-9571 E-mail: [email protected] Foundation Project: Supported by Hamad Medical Corporation (Ref #.13139/13).
delivery and newborn serious respiratory morbidity [5], respiratory distress [6] , transient tachypnea of the newborn[7], birth trauma[8], child obesity[9], and decrease rate of breastfeeding[10]. The aim of this study was to analyze the risk of acquiring respiratory syncytial virus (RSV) bronchiolitis in children delivered via the mode of C-section. 2. Materials and methods Our study was descriptive and retrospective and was administered at Hamad Medical Corporation, the only tertiary center in Qatar. Infants and children ages 0 to 36 months hospitalized with acute bronchiolitis from January 1, 2010 to December 31, 2012 were included in the study. T he following data were collected: age at diagnosis, gestational age, sex, respiratory virus polymerase chain reaction (RV-PCR) and mode of delivery. The RSV positive group included children admitted for bronchiolitis and RV-PCR was positive for RSV, and the RSV negative group is defined as children with clinical bronchiolitis but the RVPCR was negative.
S135
Mohamed A. Hendaus et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
The diagnosis of bronchiolitis was based on the American Academy of Pediatrics definition[11]. RV - PCR for commonly diagnosed respiratory viruses
was done by obtaining nasal secretions from each patient. Patients with no RV-PCR or no proper documentation of the mode of delivery were excluded. Approval for the study was obtained from Hamad Medical Corporation-Ethics Committee (Ref #13139/13). D escriptive statistics were used to summarize demographic and all other clinical characteristics of the participants. Q uantitative data values were expressed as frequency along with percentage and mean依SD with median and range. The primary outcome variable is odds of acquiring RSV bronchiolitis in children born via C-section with 95% confidence interval (CI). Quantitative variables means between two and more than two independent groups were analyzed using unpaired ‘t’ test and O ne way ANOVA . P air-wise comparisons were made using B onferroni multiple comparison test where an overall group difference was found statistically significant. The results were presented with the associated 95 % CI. I n addition, for non-normal or skewed data, Mann-Whitney U and Kruskal-Wallis tests were applied. Logistic regression analysis results were presented in terms of odds ratio (OR) and associated 95% CI. A two-sided P value <0.05 was considered to be statistically significant. All statistical analyses were done using statistical packages SPSS 19.0 (SPSS Inc., Chicago, IL). 3. Results A total number of 836 pediatric patients with acute bronchiolitis were admitted to the pediatric ward during the study period of January 1, 2010 till December 31, 2012. W e excluded 66 patients because RV - PCR was not performed on them. O f the remaining 770 patients, we had to exclude an additional 92 cases since the mode of delivery was not documented. The mean age at diagnosis was ( 3 . 61 依 3 . 56 ) months ranged from 10 d to 34 months. There were approximately 60% boys and 40% girls. The mean gestational age was (37.01依3.37) weeks ranged from 25 to 42 weeks, and less than 20 % of infants had been delivered with gestational age fewer than 35 weeks. Factors associated with mode of delivery are presented in Table 1. The mean age in the RSV-positive group was (3.43依3.63) months compared to (2.95依2.36) months in the RSV-negative group.
Table 1 Factors associated with mode of delivery.
Factors RV-PCR status
NSVD
Out of the 678 patients, 493 (72.7%) were delivered via the mode of NSVD and 185 via C-section (27.3%). For the NSVD group, RSV was positive in 215 patients (43.6%), RSV negative in 92 (18.7%) and other than RSV in 186 (37.7%). For the C-section group, 89 tested RSV positive (48.1%), 35 RSV negative (18.9%) and 61 were positive for viruses other than RSV (33.0%). The percentage of RSV bronchiolitis was observed to be higher in C-section delivery compared to NSVD (48.1% vs. 43.6%, P=0.485). Furthermore, logistic regression analysis revealed that the risk of RSV bronchiolitis was observed to be higher among C-section delivery compared to NSVD [OR=1.10; 95% CI (0.57, 1.80); P=0.965]. Gestational age ≤35 weeks was significantly associated with increased risk of RSV bronchiolitis compared to gestational age >35 weeks [OR=3.12; 95% CI (1.53, 6.38); P=0.002].
4. Discussion There are few studies in the literature mentioning the risk of cesarean delivery as a risk factor for lower respiratory infections. I n a large cohort study, M oore et al. found that 4.1% of the overall acute lower respiratory infections hospitalization rate was due to delivery by C-section[1]. C esarean delivery might lead to decrease the infant immunity, hence increase the risk of early viral lower respiratory infections[11]. RSV bronchiolitis is considered as one of the main diagnoses for hospitalized infants with a rate of 25 . 2 per 1 000 infants[12], and a main source of morbidity in the outpatient settings[13]. T he risk of RSV mortality is usually higher in infants born premature or with low birth weight[12]. Children under 2 years of age born via the cesarean mode have an increased risk of bronchiolitis with an incidence rate ratio that ranges between 1.11 and 1.20[11]. Our study did not echo the risk; we found that infants born via C-section had no higher risk of acquiring RSV bronchiolitis. I n a large retrospective study that included 1 284 newborns delivered by elective caesarean, Z anardo et al. concluded that respiratory distress syndrome risk was increased in infants born earlier than 38 weeks and 6 days[14]. However, there was no significant risk of respiratory distress syndrome in infants born at 39 weeks and above via cesarean compared to NSVD[15].
RSV positive 215 (43.6%) RSV negative 92 (18.7%) Other than RSV 186 (37.7%) Gender Male 295 (59.8%) Female 198 (40.2%) Age at diagnosis (months) Mean依SD [median (range)] 3.56依3.52 [2.47 (0.33-33)] Gestational age (weeks) Mean依SD [median (range)] 37.84依2.77 [39 (25-42)]
C-section
Total
P-value*
127 (18.7%)
0.485
438 (59.5%)
0.467
3.61依3.56 [3 (0.33-34)]
0.958 <0.001
89 (48.1%)
304 (44.8%)
61 (33.0%)
247 (36.5%)
35 (18.9%) 105 (56.7%) 80 (43.3%)
3.58依3.52 [3 (0.4-34)]
35.36依3.86 [37 (25-42)]
298 (40.5%)
37.01依3.37 [38 (25-42)]
NSVD: Normal spontaneous vaginal delivery; P-value computed using Chi-square, unpaired t test, Mann-Whitney U test. *
S136
Mohamed A. Hendaus et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S134-S136
Some authors mentioned that children born via cesarean had an increased risk of asthma later in childhood[16-19]. However, other authors do not agree[20-23]. Moreover, Bager et al. reported an increased risk of allergic rhinitis and asthma[24]. Our study as well as the studies referred to in this paper, analyzed the association between RSV bronchiolitis and the mode of delivery. However, it might be merely an association while the pathophysiology is still unknown. O ur limitation could be attributed to the number of patients born by C -section, and almost 100 patients lacked the documentation of their mode of delivery as they were born outside our health care facility. We also have inadequate information about genetic factors, and pregnancy circumstances. Since it was a retrospective study, we did not have full control of all variables and we lacked the information of whether the C-sections were performed electively or on an emergency basis. Our study will open a new scope for larger studies. Delivery by C-section does not appear to increase the risk of RSV bronchiolitis in infants compared with NSVD.
Conflict of interest statement The authors report no conflicts of interest in this work. Acknowledgements W e would like to thank D r. P rem C handra from the Medical Research Center at Hamad Medical Corporation in Qatar, who took time out of his intense schedule to assist in data analysis. Hamad Medical Corporation (Ref #.13139/13) provided US dollars of 6 850.
References [1] Moore HC, de Klerk N, Richmond P, Lehmann D. A retrospective population-based cohort study identifying target areas for prevention of acute lower respiratory infections in children. BMC Public Health 2010; 10: 757. [2] Yorita KL, Holman RC, Sejvar JJ, Steiner CA, Schonberger LB. Infectious disease hospitalizations among infants in the United States. Pediatrics 2008; 121(2): 244-252. [3] Feng XL, Wang Y, An L, Ronsmans C. Cesarean section in the People’s Republic of China: current perspectives. Int J Womens Health 2014; 6: 59-74. [4] Xie RH, Lei J, Wang S, Xie H, Walker M, Wen SW. Cesarean section and postpartum depression in a cohort of Chinese women with a high cesarean delivery rate. J Womens Health (Larchmt) 2011; 20(12): 1881-1886. [5] Hansen AK, Wisborg K, Uldbjerg N, Henriksen TB. Risk of respiratory morbidity in term infants delivered by elective caesarean section: cohort study. BMJ 2008; 336(7635): 85-87. [6] G erten KA , C oonrod DV , B ay RC , C hambliss LR . C esarean
delivery and respiratory distress syndrome: does labor make a difference? Am J Obstet Gynecol 2005; 193(3 Pt 2): 1061-1064. [7] Fogelson NS, Menard MK, Hulsey T, Ebeling M. Neonatal impact of elective repeat cesarean delivery at term: a comment on patient choice cesarean delivery. Am J Obstet Gynecol 2005; 192(5): 14331436. [8] Moczygemba CK, Paramsothy P, Meikle S, Kourtis AP, Barfield WD , K uklina E , et al. R oute of delivery and neonatal birth trauma. Am J Obstet Gynecol 2010; 202(4): 361.e1-e6. [9] Huh SY, Rifas-Shiman SL, Zera CA, Edwards JW, Oken E, Weiss ST, et al. Delivery by caesarean section and risk of obesity in preschool age children: a prospective cohort study. Arch Dis Child 2012; 97(7): 610-616. [10] Liu X, Zhang J, Liu Y, Li Y, Li Z. The association between cesarean delivery on maternal request and method of newborn feeding in China. PLoS One 2012; 7(5): e37336. [11] American Academy of Pediatrics Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics 2006; 118(4): 1774-1793. [12] L eader S , K ohlhase K . R espiratory syncytial virus-coded pediatric hospitalizations, 1997 to 1999. Pediatr Infect Dis J 2002; 21(7): 629-632. [13] Hall CB, Weinberg GA, Iwane MK, Blumkin AK, Edwards KM, Staat MA, et al. The burden of respiratory syncytial virus infection in young children. N Engl J Med 2009; 360(6): 588-598. [14] Z anardo V , S imbi AK , F ranzoi M , S old à G , S alvadori A , Trevisanuto D. Neonatal respiratory morbidity risk and mode of delivery at term: influence of timing of elective caesarean delivery. Acta Paediatr 2004; 93(5): 643-647. [15] M oore HC , de K lerk N , H olt P , R ichmond PC , L ehmann D . Hospitalisation for bronchiolitis in infants is more common after elective caesarean delivery. Arch Dis Child 2012; 97(5): 410-414. [16] Thavagnanam S, Fleming J, Bromley A, Shields MD, Cardwell CR. A meta-analysis of the association between caesarean section and childhood asthma. Clin Exp Allergy 2008; 38: 629-633. [17] Adams M, Doull I. Birth by caesarean section and asthma. Clin Exp Allergy 2008; 38: 554-556. [18] Tollånes MC, Moster D, Daltveit AK, Irgens LM. Cesarean section and risk of severe childhood asthma: a population-based cohort study. J Pediatr 2008; 153: 112-116. [19] Roduit C, Scholtens S, de Jongste JC, Wijga AH, Gerritsen J, Postma DS, et al. Asthma at 8 years of age in children born by caesarean section. Thorax 2009; 64: 107-113. [20] Almqvist C, Cnattingius S, Lichtenstein P, Lundholm C. The impact of birth mode of delivery on childhood asthma and allergic diseases--a sibling study. Clin Exp Allergy 2012; 42(9): 1369-1376. [21] Maitra A, Sherriff A, Strachan D, Henderson J; ALSPAC Study Team. Mode of delivery is not associated with asthma or atopy in childhood. Clin Exp Allergy 2004; 34: 1349-1355. [22] Werner A, Ramlau-Hansen CH, Jeppesen SK, Thulstrup AM, Olsen J. Caesarean delivery and risk of developing asthma in the offspring. Acta Paediatr 2007; 96: 595-596. [23] Menezes AM, Hallal PC, Matijasevich AM, Barros AJ, Horta BL, Araujo CL, et al. Caesarean sections and risk of wheezing in childhood and adolescence: data from two birth cohort studies in Brazil. Clin Exp Allergy 2011; 41: 218-223. [24] Bager P, Wohlfahrt J, Westergaard T. Caesarean delivery and risk of atopy and allergic disease: meta-analyses. Clin Exp Allergy 2008; 38: 634–642.