NEONATAL ADRENERGIC-BLOCKADE FOLLOWING SINGLE-DOSE MATERNAL LABETALOLADMINISTRATION

A single 30 mg intravenous dose of labetalol given 20 minutes prior to cesarean delivery at 35 weeks of gestation for severe pregnancy-induc ed hypertension was associated with symptoms of beta-adrenergic blocka de (hypoglycemia, bradycardia, hypotension) in preterm twins. The infa nts were subsequently found to have therapeutic labetalol concentratio ns (180 and 150 ng/mL) in umbilical cord blood. The pharmacology of tr ansplacental labetalol is reviewed and potential mechanisms for neonat al beta-adrenergic blockade are discussed.