Study finds that vaginal birth after previous caesarean section is associated with an increased risk of pelvic floor surgery

Published on Tuesday, 22 November 2022 Post

In an assessment of over 45,000 births in Scotland to women with one or more previous caesarean sections followed up for an average of just over 22 years, researchers at Oxford Population Health's National Perinatal Epidemiology Unit (NPEU) have found that vaginal birth is associated with an increased risk of pelvic floor surgery compared with planning another caesarean section.

The findings are intended to provide information to help women who have had a previous caesarean section when planning how to give birth in their next pregnancy.

In the UK, over 30% of births now occur by caesarean section and current guidelines recommend that pregnant women who had a previous caesarean section should be counselled on the risks and benefits of planning another caesarean compared to planning a vaginal birth so that they can make an informed decision about this choice. There has so far been limited evidence about how this choice affects women's subsequent risk of experiencing pelvic floor disorders, including pelvic organ prolapse, urinary incontinence, rectal prolapse, and faecal incontinence.

The study included data from 47,414 births in Scotland to women with one or more previous caesarean sections. All births took place between January 1983 and December 1996, were at full term, and were for just one baby. Almost 67% of the women giving birth had planned for a vaginal birth, and 33% had planned another caesarean. The women were followed up for an average of just over 22 years.

Key findings:

• 1,159 of the women studied had pelvic floor surgery;
• Women who had planned a vaginal birth rather than another caesarean were more than twice as likely to go on to have pelvic floor surgery (adjusted hazard ratio [aHR] 2.38, 95% CI 2.03-2.80, p<0.001);
• The risk of surgery for pelvic organ prolapse was three times more likely and urinary incontinence twice as likely in those who had planned a vaginal birth (aHR 3.17, 95% CI 2.47-4.09, p<0.001 and aHR 2.26, 95% CI 1.79-2.84, p<0.001, respectively);
• The risks of requiring surgery were only found in women who gave birth vaginally as planned. Women who had planned a vaginal birth but gave birth via an unplanned caesarean when they were in labour had a comparable risk to those who had planned another caesarean.

Dr Kate Fitzpatrick, lead author at Oxford Population Health, said 'Our study shows that for pregnant women who have had a caesarean birth in the past, those who have a vaginal birth rather than plan another caesarean are more likely to go on to have an operation for some type of pelvic floor disorder such as urinary incontinence. Our findings provide important new information to counsel the increasing numbers of women who have had a caesarean birth in the past about the risks and benefits associated with their future birth choices. However, this is not the only information pregnant women who have had a caesarean birth previously should consider when thinking about how to give birth. For example, they may wish to consider how many more children they would like to have, as the chances of having serious complications in future pregnancies increases with each caesarean birth. '

The results are published today in PLOS Medicine.