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When to Deliver: A New Approach to Gestational Hypertension and Mild Preeclampsia

Induction of labor at 37 weeks' gestation proved beneficial in limiting disease progression.

About 6% to 8% of pregnancies are affected by hypertensive disorders, most often after 36 weeks' gestation. In a multicenter, randomized controlled trial in the Netherlands, researchers assessed the benefits of expectant monitoring versus induction of labor in 756 women with singleton pregnancies (gestation range, 36–41 weeks) who had gestational hypertension (GHTN) or mild preeclampsia. The primary outcome was a composite score for evaluating poor maternal outcomes defined by maternal mortality and morbidity (eclampsia, HELLP syndrome [hemolysis, elevated liver enzymes, and low platelet count], pulmonary edema, thromboembolic disease, and placental abruption), progression to severe disease, and major postpartum hemorrhage (PPH).

Overall, 117 (31%) of the women randomized to induction and 166 (44%) to expectant monitoring had poor maternal outcomes as defined by composite scores (relative risk, 0.71; P<0.0001). Composite risk for poor maternal outcomes was primarily ascribed to progression to severe disease. Almost half of the women who were assigned to expectant monitoring eventually underwent induced labor (of these, 72% had at least 1 medical indication for induction). Fewer women in the induction group than in the expectant monitoring group underwent cesarean deliveries, but the difference was not statistically significant. Induction was not associated with lower rates of PPH. In a subanalysis, no beneficial effect of induction was found for pregnancies at 36 to 37 weeks' gestation. However, the study was not adequately powered to detect differences in this gestational age group.

Comment: The results of this well-designed study of labor induction in women with GHTN or mild preeclampsia likely will shift practice patterns toward induction and delivery at 37 weeks' gestation to avoid disease progression. The subanalysis at 36 to 37 weeks' gestation could not be used to predict outcomes, whether for mother or baby; however, after 37 weeks' gestation, fetuses should be able to tolerate delivery better than they would at 36 to 37 weeks.

— Diane J. Angelini, EdD, CNM, FACNM, FAAN, NEA-BC

Published in Journal Watch Women's Health September 17, 2009

Citation(s):

Koopmans CM et al. Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks' gestation (HYPITAT): A multicentre, open-label randomised controlled trial. Lancet 2009 Aug 4; [e-pub ahead of print]. (http://dx.doi.org/10.1016/S0140-6736(09)60736-4)