Indications for induction of labour and mode of delivery in nulliparous term women with an unfavourable cervix Abstract

Yannie YY CHAN1, Tsz-Kin LO1, Ellen LM YU2, Lai-Fong HO1
1 Department of Obstetrics and Gynaecology, Princess Margaret Hospital, Hong Kong
2 Clinical Research Centre, Princess Margaret Hospital, Hong Kong

Objectives: To determine the association between indications for induction of labour (IOL) and mode of delivery in nulliparous women with unfavourable cervix.
Methods: We identified nulliparous singleton term women with an unfavourable cervix who underwent IOL between 1 January 2013 and 31 December 2017 in an obstetrics unit. Clinical data of patients and their neonates were collected. The primary outcome was the mode of delivery (vaginal vs caesarean). Secondary outcomes were the instrumental delivery rate, indications for caesarean section, and maternal and neonatal complication stratified by indications of IOL.
Results: 1156 women were included for analysis. The IOL success (vaginal delivery) rate was 66.4%, the instrumental delivery rate was 19.2%, and the caesarean delivery rate was 33.6%. After controlling the confounding factors (maternal age, stature, weight gain during pregnancy, and Bishop score), indications for IOL independently associated with the mode of delivery were post-date pregnancy (adjusted odds ratio [adjusted OR]=2.30, p<0.001), diabetes mellitus diseases (adjusted OR=1.67, p=0.015), hypertensive disorders (adjusted OR=1.72, p=0.015), and large-for-gestational-age fetus (adjusted OR=2.32, p=0.001). Maternal age ≥35 years, body mass index ≥25 kg/m2, more weight gain during pregnancy were associated with caesarean section, whereas taller stature and a more favourable Bishop score were associated with vaginal delivery.
Conclusion: Different indications for IOL affect the mode of delivery differently. Post-date pregnancy, diabetes mellitus diseases, hypertensive disorders, and large-for-gestational-age fetus are independent risk factors for caesarean delivery.
Hong Kong J Gynaecol Obstet Midwifery 2021; 21(2):69–75
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