Objectives In the general population, planned caesarean section is thought to be safer in high-risk situations as it avoids the greater risk of an emergency caesarean section. Only limited data exist on the optimal mode of delivery in women with structural heart disease. We investigated the relationship between mode of delivery and pregnancy outcome in women with pre-existing heart disease.

Methods The Registry on Pregnancy and Cardiac Disease is an on-going, global, prospective observational registry of women with structural heart disease. We report on 1262 deliveries, between January 2007 and June 2011.

Results The caesarean section was planned in 393 women (31%): 172 (44%) for cardiac and 221 (56%) for obstetric reasons of whom 53 delivered by emergency caesarean section. Vaginal delivery was planned in 869 (69%) women, of whom 726 (84%) actually delivered vaginally and 143 (16%) had an emergency caesarean section. Perinatal mortality(1.1 vs 2.7, p=0.14) and low apgar score (11.9 vs 10.1, p=0.45) were not significantly different in women who had a caesarean section or vaginal delivery; gestational age(37 vs 38 weeks p=0.003) and birth weight (3073 vs 2870 g p<0.001) were lower in women delivered by caesarean section compared with women delivered by vaginal delivery. In those delivered by elective or emergency caesarean section, there was no difference in maternal mortality (1.8% vs 1.5%, p=1.0), postpartum heart failure (8.8% vs 8.2% p=0.79) or haemorrhage (6.2% vs 5.1% p=0.61).

Conclusions These data suggest that planned caesarean section does not confer any advantage over planned vaginal delivery, in terms of maternal outcome, but is associated with an adverse fetal outcome.