Role of antihypertensive therapy in mild to moderate pregnancy-induced hypertension: a prospective randomized study comparing labetalol with alpha methyldopa

Abstract

Pregnancy-induced hypertension (PIH) is associated with adverse fetal and maternal outcome. The role of medication to control blood pressure (BP) in mild to moderate PIH is controversial. We conducted a prospective study to investigate whether pharmacological treatment of mild to moderate PIH is effective in improving maternal and fetal outcomes. A total of 150 consecutive pregnant women without proteinuria and with physician-recorded systolic BP of 140-160 mmHg and/or diastolic BP of 90-105 mmHg on two occasions ≥6 h apart between 20 and 38 weeks of gestation were randomly allocated to receive either labetalol or methyldopa (50 patients each) plus standard care (treatment group) or only standard care (50 patients) (control group). As compared to the control group, the treatment group had lower rates of severe PIH (28% vs. 10%, P = 0.005), proteinuria (28% vs. 12%, P = 0.016), hospitalization before term (28% vs. 14%, P = 0.041), and delivery by cesarean section (38% vs. 22%, P = 0.042). In a multivariable logistic regression model that adjusted for maternal age, weight, parity, previous PIH, and baseline hemoglobin, resting heart rate, and BP levels, antihypertensive therapy was associated with a lower incidence of adverse maternal events (P = 0.011). Compared to the control group, the treatment group had lower incidence of SGA babies (40% vs. 23%, P = 0.033), preterm birth (36% vs. 14%, P = 0.002), and admission to neonatal unit (30% vs. 15%, P = 0.036). After adjustment for maternal age, weight, baseline hemoglobin, resting heart rate, BP level, parity and previous history of PIH, fetal death, preterm delivery or SGA baby, antihypertensive therapy was associated with a lower incidence of adverse perinatal events (P = 0.016). Maternal and perinatal mortality rates were not significantly different between treatment and control groups. In conclusion, pharmacological treatment of mild to moderate PIH is associated with lower rate of some maternal and fetal-neonatal non-fatal adverse events compared to no routine use of antihypertensive therapy.