Trying for vaginal birth after previous C-section is safe, study shows

But UAlberta research shows there is a small but higher risk of adverse outcomes for mom and baby than opting for a repeat C-section.


Women and their health-care practitioners have some new evidence to help inform and guide the mode of delivery choice after a previous caesarean section.

“The decision to try for a vaginal birth after C-section (VBAC) or elective repeat caesarean section (ERCS) is complex because there are benefits and risks with both options, outcomes are difficult to predict and the desire for vaginal birth varies among women,” explained Carmen Young, a University of Alberta maternal fetal medicine specialist and study investigator.

“Our study showed that either option is reasonable, because the risk of a serious complication for the mom or the baby is low—with the risk of uterine rupture or infant death well under one per cent of all births—if they either try a VBAC or an ERCS.”

The researchers, who examined Canadian data from 2003 to 2015, found that when the maternal and infant risks for women trying for a VBAC are compared with the risks for women choosing an ERCS, there is a significantly higher risk of serious adverse maternal and neonatal outcomes for women who try for VBAC.

“Uterine rupture was six times more likely, mother morbidity and mortality was two times as likely, and infant morbidity and mortality were one and a half times more likely for those trying to have a VBAC compared with ERCS,” said Young.

On the other hand, the study showed that women who choose and have a successful VBAC have lower rates of adverse outcomes for themselves and their babies—about half the risk—compared with ERCS.

“This highlights the importance of appropriate patient selection for attempting VBAC and careful monitoring of their labour and delivery to optimize safety for those women and their infants,” said Young. “When this occurs, either option is reasonable.”

One surprising finding—that infant outcomes after VBAC worsened over the study time period—may be attributable to a number of factors, noted Young.

“This may be related to changes in obstetrical practice, a possible decline in obstetricians with the expertise to manage VBAC and possibly changes in women’s personal characteristics, such as increasing obesity.”

A very personal choice

“For women who are considered candidates for an attempted VBAC, the choice between attempting VBAC and ERCS depends on her evaluation and interpretation of risks, as this is very personal,” explained Young.

“While the overall chance of severe maternal or infant complications is small, the risks are substantially higher for women attempting VBAC compared with ERCS. Each woman has to interpret these based on her risk tolerance. Some women may feel these risks are unacceptably high; other women may have a strong desire for vaginal birth and may feel these risks are acceptable.”

Whether a woman is planning a small or large family is also important because repeated C-sections are associated with increasing maternal and infant risks, added Young.

The study, “Mode of Delivery After a Previous Caesarean Birth, and Associated Maternal and Neonatal Morbidity,” was published in the Canadian Medical Association Journal and funded by the Canadian Institutes of Health Research and the British Columbia Children’s Hospital Research Institute.