Effect of labetalol infusion on uterine and fetal hemodynamics and fetal cardiac function.

The effect of intravenously-administered labetalol (1 mg/kg) on uterine and fetal hemodynamics and fetal cardiac function was studied in 13 women with pregnancy-induced hypertension. Maternal mean blood pressure had decreased significantly by the end of the labetalol infusion and 30 min later. The pulsatility indices reflecting peripheral vascular resistance did not change in the main uterine, placental arcuate, umbilical, and fetal middle cerebral and renal arteries, nor did the parameters reflecting fetal cardiac function. A subgroup of seven patients with a more pronounced decrease in maternal blood pressure and three cases with original signs of fetal asphyxia did not react hemodynamically in a different manner from the group as a whole with respect to the circulatory effects of labetalol. These findings obtained by Doppler and colour Doppler methods in as comprehensive manner as possible seem to demonstrate a wide tolerance of maternal and fetal hemodynamics to the moderate decrease in maternal blood pressure achieved by labetalol infusion under short-term conditions in cases of pregnancy-induced hypertension.