Does induction of labour in nulliparous hypertensive women result in vaginal birth? : a descriptive study utilising birth registry data

Background: Induction of labour (IOL) is a common procedure yet we have little information on the efficacy of the process for women with a hypertensive disorder of pregnancy (HDP). Objective: To describe the birth type and associated factors in nulliparous HDP women undergoing an induction of labour. Study design: Statutorily collected datasets on every birth and hospital admission which occurred in the state of NSW Australia between the years 2000–2011 were analysed. Hypertensive women were compared to normotensive women. Results: Of the nulliparous women, 9.9% had a HDP. IOL for HDP women were 56.2% in a cohort of 447 558 women. The AOR for a woman with a HDP undergoing an IOL resulting in a vaginal delivery when compared to a normotensive woman is 0.86 (95% CI 0.83–0.88). Prior to 33 weeks, the lowest perinatal mortality rates (PMR) are seen in women who undergo elective caesarean section (C/S). For women with preeclampsia (PE), lower PMR are seen in women who undergo IOL. Conclusion: For women with PE and SPE, IOL resulted in lower rates of vaginal delivery than spontaneous labour when compared to normotensive women who also underwent IOL. Women with PE at ≥33 weeks who underwent IOL had the lowest PMR.