Trends and outcomes of induction of labour among nullipara at term

Abstract

Aim: To determine induction trends and delivery, maternal and neonatal health outcomes by gestational age following induction at term for women having a first baby.

Methods: Linked birth and hospital data were used to examine the rates of adverse maternal and neonatal health outcomes for the period 2001-2007, among the 212,389 nullipara with singleton cephalic-presenting fetuses delivering between 37(0) and 41(6) weeks of gestation. Rates of caesarean delivery, neonatal transfers and overall severe neonatal and maternal adverse outcomes were determined by gestational age.

Results: Between 1990 and 2008, nulliparous term inductions as a proportion of all births increased from 5518 (6.8%) to 11,166 (12.5%). More than 60% of these inductions are performed before 41 weeks. Among induced nullipara, 30.4% delivered by caesarean section. Adverse neonatal outcomes and transfer rates were lowest at 39-40 weeks (overall 2.1 and 0.5%, respectively), regardless of labour onset. Maternal morbidity increased at 40 weeks (from 1.1 to 1.3%) for women in spontaneous labour, was relatively stable in those undergoing induction of labour between 37 and 40 weeks (1.8%) and decreased with gestational age until 40 weeks in those undergoing a prelabour caesarean delivery (from 3.1 to 0.8%).

Conclusion: NSW has high rates of both induction and caesarean section following induction. This study highlights the changes to clinical practice that may help reduce the rate of caesarean births in nullipara.