Mothers who deliver via c-section less likely to conceive again within three years, study finds

Photo: Getty Images/iStockphoto
Photo: Getty Images/iStockphoto 

Women who have a c-section are less likely to have a second child, despite being just as likely to want another baby. That's according to a new large study, which followed over 2,000 mothers for three years after giving birth.

While previous research has shown that women who have c-sections are less likely to have subsequent children, what remained unclear was whether this was due to choice or lower rates of conception.

To examine this, a team of researchers from Penn State school of medicine interviewed women before their first baby and followed them for three months post-partum. Mums were interviewed every six months and asked to report how much baby making they'd done during that time. When they analysed the data they found that around 69 per cent of women who delivered by C-section conceived a second child compared to around 78 per cent of those delivered vaginally. 

The link also remained after other factors including mum's age, pre-pregnancy BMI, how long it took to conceive their first child and other health issues were also taken into account. 

"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, even though women who delivered by caesarean were just as likely to plan to have a subsequent child within 3 years after first childbirth, to have unprotected intercourse in the 36 months following first delivery, and to begin having unprotected intercourse at an average of 13 months after first delivery," the authors explain in their paper, which has been published in JAMA Obstetrics and Gynaecology. 

According to the authors, the global average annual caesarean delivery rate has more than tripled over the past 25 years, from 6.7 per cent in 1990 to 21.1 per cent in 2015. "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 child-bearing patterns of many families, particularly in countries with high caesarean delivery rates," they continue.

The question is, why? Co-author Dr. Richard Legro believes there might be a physiological reason for the link. "It's possible that pelvic or [fallopian] tubal scarring as a result of being exposed to open air and contaminants may affect subsequent attempts at getting pregnant," Dr Legro said. "It is also possible that scar formation from the surgical wound in the uterus, though not in an area where pregnancies implant, may have lingering effects on the process of implantation."

Based on the findings, Dr Legro encourages women under 35 who don't conceive after a year of trying for a baby after a C-section to seek medical advice. 

Fertility specialist, gynaecologist and obstetrician, Dr Ben Kroon, tells Essential Baby that this is not the first study to suggest a link between caesarean delivery and a slight reduction in subsequent conception rate. "It is likely that women who have caesareans and those who have vaginal deliveries are not identical groups, and it may be something inherent to each of those groups that causes this difference, or it may be something to do with the actual caesarean itself," he says. "While this study gives us important information which may help us better understand the origin of some cases of secondary infertility, I think it's important to realise that more work is needed to confirm a link between caesarean and a delay in subsequent conception, and to identify whether there is a valid mechanism."

Dr Kroon notes that it's important to emphasise to women reading this who are struggling to conceive and who may have had a caesarean, "that there are many far more clearly defined causes of secondary infertility and that for most women the mode of delivery is unlikely to be an important factor. "