Objective: The objective was to compare the safety and efficacy of intravenous labetalol and intravenous hydralazine for acutely lowering blood pressure in pregnancy.
Study design: Two hundred women with severe hypertension in pregnancy were randomized to receive hydralazine (5 mg as a slow bolus dose given intravenously, and repeated every 20 min up to a maximum of five doses) or labetalol (20-mg intravenous bolus dose followed by 40 mg if not effective within 20 min, followed by 80 mg every 20 min up to a maximum dose of 300 mg). The primary end point was successful lowering of blood pressure and maternal hypotension.
Results: Women were similar with respect to characteristics at randomization. No significant differences were observed for maternal hypotension or persistent severe hypertension; only two patients in the hydralazine group presented with hypotension. Palpitations (p=0.01) and maternal tachycardia (p=0.05) occurred significantly more often in patients treated with hydralazine. The main neonatal outcomes were very similar per group; however, hypotension and bradycardia were significantly more frequent in the labetalol group. There were two neonatal deaths per antihypertensive drug group.
Conclusions: This randomized clinical trial shows that labetalol and hydralazine fulfill the criteria required for an antihypertensive drug to treat severe hypertension in pregnancy.