Association Between Mode of First Delivery and Subsequent Fecundity and Fertility

Abstract

IMPORTANCE More than 20% of births globally are by cesarean delivery, including more than 30% in the US. Prior studies have reported lower rates of childbearing after cesarean delivery, but it is not clear if this is due to maternal choice or lower conception rates. OBJECTIVE To investigate the association between mode of first delivery and subsequent conceptions and live births. DESIGN, SETTING, AND PARTICIPANTS The First Baby Study was a multicenter prospective cohort study of women aged 18 to 35 years with singleton pregnancies, enrolled and interviewed before first childbirth, who delivered in Pennsylvania from 2009 to 2011 and were followed up for 36 months after delivery (until April 2014). Data analysis for this study took place between May and July 2019 and in January 2020. EXPOSURES Mode of first delivery (cesarean or vaginal). MAIN OUTCOMES AND MEASURES Rates of subsequent conceptions and live births. Discrete-time Cox proportional hazard regression models were used to compare the rate of subsequent conception (vaginal vs cesarean) among those who completed the 36-month survey, accounting for reported months of unprotected intercourse during the follow-up period and adjusting for relevant covariates. A log binomial regression was used to compare the age-adjusted rate of subsequent live birth (vaginal vs cesarean) among those who completed the 36-month survey. RESULTS The study population consisted of 2423 women who were retained to the 36-month survey (mean [SD] age at baseline was 27.2 [4.4] years and 712 [29.4%] delivered by cesarean). There were 2046 women who had unprotected intercourse during the follow-up period, 2021 of whom provided data on months of unprotected intercourse. Cesarean delivery was associated with lower rates of conception after unprotected intercourse during the follow-up period (413 of 599 [68.9%]) compared with vaginal delivery (1090 of 1422 [76.7%]) (adjusted hazard ratio, 0.85; 95% CI, 0.74-0.96). Cesarean delivery was also associated with reduced likelihood of a subsequent live birth (305 women [42.8%]) compared with vaginal delivery (857 women [50.1%]), with an age-adjusted risk ratio of 0.83 (95% CI, 0.75-0.92). CONCLUSIONS AND RELEVANCE In the 3 years following first childbirth, women who delivered their first child by cesarean had lower rates of conception after unprotected intercourse, and fewer of these women had a second child than those who delivered vaginally.

Assessment of Cesarean Delivery and Neurodevelopmental and Psychiatric Disorders in the Children of a Population-Based Swedish Birth Cohort

“…They also provide less precise estimates owing to reduced statistical power and are more susceptible to nonshared confounding. 51 Moreover, both the studied exposures and outcomes may lead to a reproductive stoppage 52 , 53 , 54 , 55 , 56 in the family that may potentially threaten the generalizability of sibling results. In our cohort, mothers who delivered via CD were more likely to curtail their reproduction than mothers who delivered vaginally.…”

Natural history of urinary incontinence from first childbirth to 30-months postpartum

“…The First Baby Study (FBS) was designed and statistically powered to investigate the association between mode of delivery at rst childbirth and subsequent childbearing. Information about the study power calculations, sample representativeness, and ow diagram of participants have been reported elsewhere [14,15]. The study participants were more likely to be white, college educated, married and to have private insurance than women in the state of Pennsylvania as a whole at rst childbirth, but did not differ by mode of delivery [14,15].…”

“…Information about the study power calculations, sample representativeness, and ow diagram of participants have been reported elsewhere [14,15]. The study participants were more likely to be white, college educated, married and to have private insurance than women in the state of Pennsylvania as a whole at rst childbirth, but did not differ by mode of delivery [14,15]. A planned secondary analysis of the FBS was to study the progression of urinary incontinence over the course of the study period.…”

Factors associated with ewe and lamb survival, and subsequent reproductive performance of sheep undergoing emergency caesarean section

“…A 93.3% conception rate in the 89 animals retained for breeding and unassisted parturition in 84.4% of the 77 cases with available data on subsequent lambing ease are both well within the normal range (Parkinson et al., 2019a; Waage & Wangensteen, 2013). Potential mechanisms that might lead to reduced pregnancy rates following caesarean surgery in the female include uterine scar formation, which may negatively affect subsequent placentation (Kjerulff et al., 2020). Inflammatory processes may lead to post‐operative adhesions and thus to impaired or delayed uterine involution.…”