Birth by caesarean section is unlikely to cause problems with future fertility, say researchers from the Royal College of Obstetricians and Gynaecologists (RCOG) and the London School of Hygiene and Tropical Medicine, in a new study published today in Human Reproduction.
Previous studies have reported that delivery by caesarean section is associated with fewer subsequent pregnancies and babies, as well as longer intervals between pregnancies. This has caused concern, particularly as caesarean section has become much more frequent over the last 20 years.
This new study looks at over 1 million, low-risk, first-time mothers who gave birth in English NHS hospitals between 1 April 2000 and 31 March 2012. It found that the medical and social circumstances leading to the decision to carry out a caesarean section may be associated with the apparent reduction in fertility, rather than the procedure itself.
Among low-risk first-time mothers, 224,024 (21.4%) were delivered by caesarean section, with less than 4% having an elective caesarean section. All types of caesarean section were associated with a reduced subsequent birth rate, compared with those who had vaginal deliveries, but the size of reduction varied among different groups of women. The reduction was smallest for elective caesarean section for a breech baby among women who had no other complications during their pregnancy. The reduction in subsequent birth rates was largest for women having an elective caesarean section for a medical indication.
Dr Tahir Mahmood, from the Office for Research and Clinical Audit at the RCOG and co-author of the paper said:
“The possible effect of caesarean section on subsequent fertility is important as the age of first time mothers continue to rise, along with the rates of caesarean section.
“This is the largest cohort study to date looking at the association between mode of delivery and fertility, and to minimize the risk of bias we focused on low-risk pregnancies.
“By carefully distinguishing between different complications of pregnancy, we have found that having a caesarean section as a first-time mother leads to only a very small effect on subsequent fertility. The circumstances behind the procedure may have a bigger impact and may explain the reduction in fertility apparent in previous studies.”
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“A population-based cohort study of the effect of Caesarean section on subsequent fertility,” by I. Gurol-Urganci, D.A. Cromwell, T.A. Mahmood, J.H. van der Meulen, and A. Templeton. Human Reproduction journal. doi:10.1093/humrep/deu057