Objective To assess the effect on maternal and neonatal outcomes of the amalgamation of two maternity units (Category A and B) to form a C2 “super-centre”, and the subsequent increase in consultant labour ward cover from 40 h/week to 111 h/week.

Methods Pre- and post-amalgamation data were extracted from an electronic Maternity Information System and analysed using the relative risk.

Results N = 5422 deliveries pre-amalgamation, n = 5046 post-amalgamation. No significant difference was seen in mode of delivery, apart from an increase in the number of planned homebirths (RR 1.22 [1.01,1.46] p = 0.04), and attended homebirths (RR 1.26 [1.04,1.52] p = 0.02). There was a trend for a decrease in the number of failed instrumental deliveries (RR 0.86 [0.50,1.47] p = 0.58) but no change in success rate (RR 0.91 [0.80,1.03] p = 0.15), or emergency caesarean section rate (RR 0.96 [0.87, 1.06] p = 0.39) post-amalgamation. The only significant difference in outcomes was a 1% increase (RR 1.34 [1.09, 1.64] p = 0.005) in the number of unexpected transfers to the neonatal unit at >37 weeks gestation (p < 0.005). There was no difference in maternal transfers to the high-dependency unit, maternal deaths, or stillbirths.

Conclusions Amalgamation has improved maternal choice as there were significantly more planned/attended homebirths, however it has had little effect on maternal and neonatal outcomes in the hospital environment. Although the Royal College of Obstetrics and Gynaecologists advises 168 h/week obstetric consultant cover in large maternity units, there is conflicting evidence to support this and our data failed to demonstrate a positive effect of increased consultant presence.