Effects of the Timing of Labour Induction on Maternal and Neonatal Outcomes in Low-risk Nulliparous Chinese Women

Backgroud: When labour induction should be offered to women at or beyond term is unclear. This work aimed to investigate the effects of the timing of labour induction on maternal and neonatal outcomes in low-risk pregnancies. Methods: This retrospective case-control study involved low-risk primigravid pregnant mothers in whom labour was induced at 40-41+6 weeks at our two hospitals between January and December 2017. According to the gestational age at labour induction, participants were categorized into the study group (40-40+6 weeks, n=284) or to the control group (41-41+6 weeks, n=172), and maternal and neonatal outcomes were compared.Results: The study group showed significantly shorter labour in the first stage (391.8±225.7 vs. 472.0±268.9 min, P=0.006), second stage (65.41±38.66 vs. 53.73±31.58 min, P= 0.008) and total stage (453.0±235.8 vs. 535.7±259.8 min, P=0.005). The two groups showed no significant differences in the methods of labour induction or in the rates of failure of labour induction, of caesarean delivery, of postpartum haemorrhage, or of admission to the neonatal intensive care unit.Conclusions: Our retrospective study suggests that inducing labour at 40-40+6 weeks does not increase the risk of adverse maternal or foetal outcomes, and that it shortens labour. These results suggest that labor induction at 40-40+6 weeks was feasible for low-risk primiparas.Trial registration: The research has been approved by the Ethics Committee of West China Second Hospital of Sichuan University and Chengdu Women and Children's Central Hospital, China. Patients gave written informed consent for their anonymized medical data to be analyzed and published for research purposes.