Perinatal outcomes following an earlier post-term labour induction policy: a historical cohort study.

OBJECTIVE To assess the changes in perinatal outcomes in children born from 37 weeks of gestation after implementation of a more proactive labour induction practice from 2009. DESIGN Register-based cohort study. SETTING Denmark, 2000-12. POPULATION Newborns from 37 weeks of gestation. METHODS Perinatal outcomes were estimated using a logistic regression analysis with adjustment for gestational age, maternal age, parity, plurality, smoking and body mass index. MAIN OUTCOME MEASURES Perinatal outcomes. RESULTS A total of 770 926 infants were included. Labour induction from 37 weeks increased from 9.7% in 2000-02 to 22.5% in 2011-12. From 2003-05 to 2011-12, the risk of umbilical cord pH < 7.0 decreased by 23%; odds ratio (OR) 0.77 (95% confidence interval 0.67-0.89), and the adjusted OR of Apgar score < 7 at 5 minutes was unchanged. The risk of admission to neonatal intensive care units increased by 56%; OR 1.56 (1.47-1.66), whereas the risk of neonatal deaths decreased by 44%; OR 0.56 (0.45-0.70). The risk of cerebral palsy was from 2000-02 to 2009-10 reduced by 26%; OR 0.74 (0.60-0.90). The proportion of infants born with fetal weight ≥ 4500 g decreased by one-third; OR 0.68 (0.65-0.71). However, the risk of shoulder dystocia increased by 32%; OR 1.32 (1.21-1.44), whereas the risk of peripheral nerve injuries was reduced by 43%; OR 0.57 (0.45-0.73). CONCLUSION The results suggest an overall improvement in perinatal outcomes as a result of a more proactive post-term labour induction practice.