Maternal and neonatal outcomes of pregnancy in women with chronic hypertension: A retrospective analysis of a national register

Introduction. Pregnancies complicated by chronic hypertension are at increased risk of adverse pregnancy outcomes. To assess whether planned early delivery might prevent some of these adverse outcomes, we studied maternal and neonatal outcomes of pregnancy in women with chronic hypertension, including gestational-age-specific outcomes. Material and methods. We performed a retrospective, population-based cohort study, using data from the Netherlands Perinatal Register. We included women with chronic hypertension and normotensive controls who delivered a singleton without congenital anomalies in 2002-2007. We calculated crude and adjusted odds ratios (OR) with 95% CI, compared delivery and ongoing pregnancy using moving averages, and used multiple Cox regression to adjust for differences in baseline characteristics and to examine adverse neonatal outcomes across subgroups of hypertensive disorder. Main outcome measures were composite adverse maternal and neonatal outcomes. Results. We included 3457 (0.3%) women with chronic hypertension and 984 932 normotensive controls. Women with chronic hypertension had adverse maternal outcomes more often (28.7% vs. 6.6%, adjusted OR 5.7, 95% CI 5.3-6.2). Their offspring had an increased rate of neonatal morbidity (17.4% vs. 13.2%, adjusted OR 1.2, 95% CI 1.1-1.4) but not of severe adverse neonatal outcomes (2.5% vs. 2.2%, adjusted OR 0.8, 95% CI 0.6-1.0). The increased risk of adverse maternal outcomes for ongoing pregnancy remained stable around 17% at term. The risk of severe adverse neonatal outcomes for birth was at its lowest between 38 and 40 weeks, mainly in women with iatrogenic onset of delivery. Conclusions. Women with chronic hypertension are at increased risk of adverse maternal and neonatal outcomes compared with controls throughout pregnancy, including at term. Our results suggest that the optimal timing of delivery might be between 38 and 40 weeks of gestation, but prospective randomized studies should confirm this.