Hypertensive disease complicates up to one in 5 pregnancies and is a major risk factor for fetal illness and death—particularly the marked hypertension associated with preeclampsia. Hydralazine long has been the preferred drug for treating severe hypertension in this setting, but side effects are common and may mimic worsening preeclampsia. Intravenous labetalol, another option for treating acute hypertension in pregnancy, causes fewer side effects. There is, however, concern about neonatal bradycardia.
This study compared the 2 drugs in 200 pregnant women with severe hypertension, defined as a systolic blood pressure of at least 160 mm Hg and/or a diastolic pressure of at least 110 mm Hg while not on antihypertensive therapy. Participants were randomized to receive either hydralazine (5 mg as a slow intravenous bolus dose repeated at 20-minute intervals up to 5 doses) or labetalol (20 mg as an intravenous bolus dose followed by 40 mg if not effective within 20 minutes and than 80 mg every 20 minutes up to a maximum of 300 mg). Women in the 2 treatment groups were similar in maternal and gestational ages, hypertensive disorder, parity, baseline blood pressure, and urinary protein. In 12% of participants, the baseline diastolic blood pressure was 115 mm Hg or higher at the time of randomization.
Palpitations and maternal tachycardia were significantly more frequent in patients given hydralazine, but there were no significant group differences in maternal hypertension or persistent severe hypertension. Two hydralazine-treated women had overshoot hypotension. Neonatal hypotension and bradycardia were significantly more frequent in the labetalol group (10.6% vs 1.9%; P = .008), however, they did not result in prolonged neonatal intensive care unit admission or neonatal death. There were 2 neonatal deaths in each group; 3 of the 4 deaths were associated with delivery at or before 28 weeks gestation. None of the mothers died.
Both hydralazine and labetalol, given intravenously, are appropriate drugs for use in treating pregnant women who are severely hypertensive.