Demographics and caesarean delivery rates
Overall, there were 103,165 births in the cohort. After exclusions, 102,589 births with complete data remained for analysis: 48,215 in Group A, and 54,374 in Group B (Figure S1). On average, women in Group B were older and were more likely to be overweight or obese (Table 1). Group B also had a greater proportion of nulliparous women (50% vs 46%), and more women with a previous caesarean delivery (24% vs 14% of births to parous women, 12% vs 7.5% of all births).
The overall caesarean delivery rates were 19% in Group A and 30% in Group B (Table 2). Over the two time-periods, planned caesarean delivery increased from 9.7% to 19% and emergency caesarean delivery increased from 9.4% to 11.6% of all births (Table 2). The rate of caesarean delivery in women with no previous caesarean delivery increased from 15% to 23% and the rate in nulliparous women increased from 20% to 30%.