Comparison of Maternal and Neonatal Outcomes Following Induction of Labour at 39 Weeks versus 40 Weeks in Low-risk Pregnancies: A Retrospective Cohort Study

Introduction: Optimum timing of delivery is crucial for a healthy pregnancy outcome. The decision to terminate low-risk fullterm pregnancies, i.e., between 39 weeks 0 days and 40 weeks 6 days, has remained controversial. The risk-to-benefit ratio must be weighed in relation to the induction of labour and the prolongation of pregnancy. Aim: To compare foeto-maternal outcomes after elective induction of labour in low-risk antenatal women at 39 and 40 weeks of gestation. Materials and Methods: The present study was a retrospective cohort study conducted in the Department of Obstetrics and Gynaecology, ESIC PGIMSR Basaidarapur, New Delhi, India, from December 2020 to April 2022. Eighty low-risk pregnant women carrying a live singleton foetus in cephalic presentation, who had undergone elective induction of labour, were selected and assigned into two categories: Group A: Elective induction at 39 completed weeks (N=40), Group B: Elective induction at 40 completed weeks (N=40). Labour induction was performed according to standard institutional protocol. The primary outcome studied was the caesarean section rates. Data were analysed using Statistical Package for Social Sciences (SPSS) v25.0. Quantitative variables were summarised as mean±Standard Deviation (SD) or median {Interquartile Range (IQR)} and compared using the independent t-test. Categorical variables were expressed as numbers (%) and compared using the Chi-square or Fisher’s exact test. Results: Sociodemographic data were comparable between the two groups, with the mean age of participants being 25.7±3.48 years in the 39-week group and 25.9±3.48 years in the 40-week group. The distribution of women according to parity was comparable between the two groups. Nulliparous women comprised 24 (60%) in the 39-week cohort and 30 (75%) in the 40-week cohort, while multiparous women comprised 16 (40%) and 10 (25%) of the 39 and 40-week cohorts, respectively (p=0.152). The rate of caesarean delivery was significantly increased in women undergoing elective induction of labour at 40 weeks versus 39 weeks, at 22 (55%) vs. 11 (27.5%), respectively (p=0.013). Instrumental delivery occurred in 3 (7.5%) women induced at 39 weeks but in none induced at 40 weeks. There was a non-significant increase in postpartum haemorrhage occurred after eIOL at 40 weeks: 1 (2.5%) in the 39 weeks group versus 6 (15%) in the 40 weeks group (p=0.108). No significant between-group differences were observed in adverse neonatal outcomes. APGAR score at 1 and 5 minutes were comparable, with 3 (7.5%) and 4 (10%) babies having APGAR