Immediate delivery versus expectant monitoring for hypertensive disorders of pregnancy between 34 and 37 weeks of gestation (HYPITAT-II): an open-label, randomised controlled trial

Background There is little evidence to guide the management of women with hypertensive disorders in late preterm pregnancy. We investigated the effect of immediate delivery versus expectant monitoring on maternal and neonatal outcomes in such women. Methods We did an open-label, randomised controlled trial, in seven academic hospitals and 44 non-academic hospitals in the Netherlands. Women with non-severe hypertensive disorders of pregnancy between 34 and 37 weeks of gestation were randomly allocated to either induction of labour or caesarean section within 24 h (immediate delivery) or a strategy aimed at prolonging pregnancy until 37 weeks of gestation (expectant monitoring). The primary outcomes were a composite of adverse maternal outcomes (thromboembolic disease, pulmonary oedema, eclampsia, HELLP syndrome, placental abruption, or maternal death), and neonatal respiratory distress syndrome, both analysed by intention-to-treat. This study is registered with the Netherlands Trial Register (NTR1792). Findings Between March 1, 2009, and Feb 21, 2013, 897 women were invited to participate, of whom 703 were enrolled and randomly assigned to immediate delivery (n=352) or expectant monitoring (n=351). The composite adverse maternal outcome occurred in four (1.1%) of 352 women allocated to immediate delivery versus 11 (3.1%) of 351 women allocated to expectant monitoring (relative risk [ RR] 0.36, 95% CI 012-111; p=0069). Respiratory distress syndrome was diagnosed in 20 (5.7%) of 352 neonates in the immediate delivery group versus six (1.7%) of 351 neonates in the expectant monitoring group (RR 3.3, 95% CI 1.4-8.2; p=0.005). No maternal or perinatal deaths occurred. Interpretation For women with non-severe hypertensive disorders at 34-37 weeks of gestation, immediate delivery might reduce the already small risk of adverse maternal outcomes. However, it significantly increases the risk of neonatal respiratory distress syndrome, therefore, routine immediate delivery does not seem justified and a strategy of expectant monitoring until the clinical situation deteriorates can be considered.