(442) Late Preterm Labor Induction Outcomes in Nulliparas with Hypertensive Disorders of Pregnancy

The data regarding delivery outcomes among nulliparous individuals with hypertensive disorders of pregnancy (HDP) during the late preterm period is limited. We aimed to evaluate the rate of successful induction of labor (IOL) and risk factors for unplanned cesarean delivery (CD), among nulliparous individuals with HDP undergoing IOL in the late preterm period (34 and 37 weeks).

Study Design:

This retrospective cohort study included nulliparous pregnancies individuals with HDP who underwent IOL in the late preterm period. Those with a planned caesarean delivery (CD) were excluded. The primary outcome was mode of delivery. Logistic regression was used to identify predictors of vaginal delivery. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were calculated.

Results:

Of 6,670 individuals diagnosed with HDP during the study period, 537 (8.1%) underwent induction between 34–37 weeks. Among them, 242 (45.1%) nulliparous individuals met inclusion criteria. Of these, 155 (64.0%) had a vaginal delivery, while 87 (36.0%) underwent an unplanned CD.

Vaginal delivery was less likely in patients with severe HDP (43% vs. 70%, p< 0.001), older age (29.6 vs. 32.4 years, p< 0.001), and higher BMI (28.9 vs. 29.7, p=0.013). Maternal and neonatal outcomes were similar between the groups (Table 1). In multivariable analysis, severe HDP (aOR 3.22, 95% CI 1.72–6.01), maternal age (aOR 1.09 per year, 95% CI 1.03–1.16), and Body Mass Index (BMI) (aOR 1.09 per unit, 95% CI 1.03–1.15) independently predicted unplanned CD (Table 2). 

Conclusion:

Approximately one in three nulliparous individuals with HDP requiring induction in the late preterm period will undergo an unplanned CD. The risk is higher among those with severe disease, advanced maternal age, and elevated BMI. These findings may assist with patient counseling and guide clinical decision-making regarding induction in this population.