Effects of maternal labetalol on the newborn infant.

Forty eight neonates, born to mothers suffering from pregnancy induced hypertension and receiving labetalol for control of blood pressure, were studied for the possible adverse effects of the drug. These were compared with eighty one neonates matched for gestation and weight and born to mothers with pregnancy induced hypertension treated with drugs other than labetalol. Incidence of birth asphyxia and intrauterine growth retardation (IUGR) in the study population was 10.4 and 22.9%, respectively and in the control group 5 and 19.7%, the difference between two groups was not statistically significant (p > 0.05). However, the incidence of hypoglycemia was significantly higher (p < 0.01) in the study group (47.9%) as compared to the control group (17.2%). Two-thirds of the hypoglycemic babies in the study population were asymptomatic and they were managed with sugar-fortified milk feeds. In the study population, the symptomatic hypoglycemic babies had hypoglycemia for prolonged duration of 43.3 +/- 23.3 hours as compared to 11.5 +/- 6.3 hours in symptomatic hypoglycemic babies of the control group (p < 0.01). The mothers of the symptomatic babies in the study group received higher doses of labetalol in the range of 287.6 +/- 142.3 mg/day while rest of the mothers in the same group whose babies had either asymptomatic hypoglycemia or normal blood glucose levels, received 239.5 +/- 118.5 mg/day, though the difference was not statistically significant. It is concluded that maternal labetalol therapy is associated with increased risk of neonatal hypoglycemia.