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.