Low conception rate after Caesarean delivery

Women who underwent Caesarean delivery with their first child were less likely to have a subsequent conception than those who had vaginal delivery, according to a recent study.

“We found that Caesarean delivery was associated with lower rates of conception after unprotected intercourse during the 36-month follow-up period, and with less likelihood of having a subsequent child than women who had delivered vaginally,” said the researchers.

“As the global Caesarean delivery rate continues to rise, even a modest level of impairment in women’s ability to conceive and bear children after Caesarean delivery has the potential to affect the childbearing patterns of many families, particularly in countries with high Caesarean delivery rates,” they continued.

Using data from the First Baby Study cohort, the researchers prospectively analysed 2,423 women with singleton pregnancies (mean age 27.2 years) who either had Caesarean (n=712) or vaginal (1,711) deliveries between 2009 and 2011 in Pennsylvania, US. Participants were followed up until 36 months postpartum during which time 84.4 percent of women reported having unprotected intercourse. [JAMA Netw Open 2020;doi:10.1001/jamanetworkopen.2020.3076]

Subsequent conception rate was significantly lower in women whose previous delivery was by Caesarean section than in those who delivered vaginally (68.8 percent vs 76.7 percent; p<0.001). The findings were consistent regardless of whether the women were trying to conceive (82.3 percent vs 88.3 percent; p=0.006) or not (46.0 percent vs 54.7 percent; p=0.04).

Caesarean delivery was also associated with a significantly lower rate of subsequent live birth (42.8 percent vs 50.1 percent; p=0.001) and a higher rate of stillbirth (1.2 percent vs 0.1 percent; p=0.01) compared with vaginal delivery.

However, the researchers noted that “the number of stillbirths was too small to account for the mode of delivery difference in rate of subsequent live births.”

The results were consistent with a previous study which showed lower subsequent pregnancy and live birth rates among women with a previous Caesarean delivery compared with vaginal delivery, said the researchers. [Hum Reprod 2013;28:1943-1952]

The present study had some limitations, including the short follow-up period (3 years after the first childbirth). “Therefore, we cannot speak to the likelihood that the women in our study who delivered by Caesarean would eventually catch up to the women who delivered vaginally in terms of fecundity and fertility,” the researchers said.

“Further large-scale prospective studies are needed to measure unprotected intercourse on a month-by-month basis after first childbirth, to see if our findings can be replicated in different populations and to investigate the extent of specific pathologies following Caesarean delivery that could explain lower subsequent conception rates among women who have had a previous Caesarean delivery,” the researchers suggested.