Outcomes of nifedipine versus labetalol for oral treatment of chronic hypertension in pregnancy

Abstract

A recent randomized trial showed that treating chronic hypertension (CHTN) in pregnancy reduced risks of adverse outcomes including preeclampsia and preterm birth (PTB). We tested whether maternal and neonatal outcomes differ by use of labetalol vs. nifedipine for antihypertensive therapy in pregnancy. Planned secondary analysis of an open label RCT of antihypertensive treatment (vs. none) in pregnancy in patients with mild CHTN (BPs < 160/105 mmHg) and singleton pregnancies < 23 weeks’ gestation. Those randomized to treatment received labetalol or nifedipine. We compared outcomes of each medication vs. the no treatment and also labetalol vs. nifedipine based on initial treatment. The primary outcome was a composite of severe preeclampsia, PTB < 35weeks, placental abruption, fetal/neonatal death. Secondary outcomes included small for gestational age (SGA). Relative risks were estimated via log binomial regression. Of 2374 patients analyzed, 744 (31.3%) initially received labetalol, 430 (18.1%) nifedipine and 1200 (50.5%) no treatment. No baseline characteristics differed for labetalol vs. none, race differed for nifedipine vs. none, and race, type of CHTN and aspirin use differed for labetalol vs. nifedipine. The primary composite outcome occurred in 217(30.1%), 130(31.2%), 427(37.0%), and SGA < 10th in 85(12.0%), 41(10.0%), 117(10.4%) in the labetalol, nifedipine and no treatment groups respectively. Labetalol use (vs. none) was associated with a reduced risk of the primary composite, severe preeclampsia and PTB < 35 weeks. Nifedipine use (vs. none) was associated with reduced risks of the primary composite and PTB < 35weeks (Figure 1, Table 2; p< 0.05. No outcomes significantly differed by assignment to labetalol vs. nifedipine. No differences were observed in SGA rates (Table 2). Adjustment for baseline differences between groups did not change the results. Antihypertensive treatment with either labetalol or nifedipine appears equally effective for mild chronic hypertension in pregnancy.View Large Image Figure ViewerDownload Hi-res image Download (PPT)