Quantification of risk of emergency caesarean during labour after one previous caesarean section

In its 2007 guideline, the Royal College of Obstetricians and Gynaecologists (RCOG) recommends vaginal birth after caesarean (VBAC) as safer than repeat elective caesarean sections. However, this document does not give details of risk of emergency caesarean section for women accepting VBAC. An emergency caesarean is associated with increased maternal and neonatal morbidity, and women do consider the eventuality of emergency delivery when deciding mode of delivery. We sought to quantify this risk by designing a retrospective cohort study in a consultant-led unit. While higher than average rates of successful planned VBAC were achieved, the odds of emergency caesarean delivery were increased in women undergoing VBAC (OR 3.0, 95% CI 1.2-7.6, p = 0.03). Odds of requiring a Category 1 emergency caesarean were markedly raised. Our data adds to the VBAC literature by quantifying the risk of Category 1 or 2 emergency caesarean section for women entering labour who have delivered by caesarean section once previously, giving the odds of emergency caesarean section on entering labour compared with women without a scar. This gives further information to those counselling women about birth after caesarean section.