Single dose of labetalol in normotensive pregnancy: effects on maternal hemodynamics and uterine and fetal flow velocity waveforms

Abstract

The short-term effect of 0.8 mg/kg of intravenous bolus of labetalol upon maternal and fetal hemodynamics was investigated in 10 healthy women at 38 weeks of gestation admitted to the hospital for elective cesarean section. The maximum effect occurred within 35 min after labetalol. At that point, the mean arterial pressure had decreased by 16%, and a slight decrease was observed in maternal heart rate. As to the flow velocity waveforms, no significant change was found in mean systolic/diastolic (S/D) ratio of uterine artery, umbilical artery or fetal middle cerebral artery. However, in 2 subjects with a large decrease in blood pressure also the uterine artery S/D ratio decreased.