289 Hypertensive disorders of pregnancy and adverse outcomes among low-risk term, nulliparous patients

Abstract

To evaluate the association between hypertensive disorders of pregnancy (HDP) and adverse pregnancy outcomes among low-risk nulliparous patients at 39 weeks or later. This was a secondary analysis of a multicenter randomized trial of labor induction versus expectant management in low-risk nulliparous participants. The analytic cohort consisted of those who delivered on or after 39 0/7 weeks gestational age (GA) in the expectant management group. The primary outcome was a composite of adverse maternal outcomes (i.e., placental abruption, pulmonary edema, postpartum hemorrhage, postpartum infection, venous thromboembolism, and intensive care unit admission). Secondary outcomes were a composite adverse perinatal outcome of perinatal death or severe neonatal complications, small or large birthweight for gestational age, and mode of delivery. We performed multivariable analysis to estimate adjusted relative risks (aRR) for binomial outcomes, adjusted odds ratios (aOR) for multinomial outcomes, 95% confidence intervals (CI), and test for interaction between HDP and GA at delivery. Of the 6106 randomized participants, 2718 (44.5%) met inclusion criteria for this analysis, of whom 373 (13.7%) developed HDP. People with HDP were more likely to identify as non-Hispanic Black, be publicly insured, have a body mass index ≥ 30 kg/m2, and have a modified Bishop score < 5 at randomization. Compared with participants without HDP, those who developed HDP had a higher risk for the composite of adverse maternal outcomes (aRR 1.84, 95% CI 1.33-2.54) and higher odds of cesarean delivery (aOR 1.32, 95% CI 1.01-1.71), but had a similar odds of operative vaginal delivery (aOR 1.26, 95% CI 0.85-1.87). The two groups did not differ in frequency of adverse perinatal outcomes (Table). The risks associated with HDP did not vary by GA at delivery. Among low-risk nulliparous participants who were expectantly managed after 39 weeks’ GA, about 14% developed HDP, and they were at higher risk of adverse maternal outcomes and had higher odds of cesarean delivery compared with those without HDP.