Effects of propranolol during pregnancy and development of rats. I. Adverse effects during pregnancy.

Pregnant rats, treated with high doses of propranolol, gave birth to small for dates neonates. Litter size was affected in daily doses of 100 and 150 mg/kg/day. Propranolol markedly influenced the gain in weight normally observed in pregnant rats. The placentas of the rats which received the higher doses of propranolol weighed about 30% less than normal placentas. Pregnant rats, treated with propranolol, gave birth to small for dates neonates. This effect is possibly the result of a drug-induced reduction in transport across cellular membranes, resulting in malnutrition. Since similar effects were reported in humans, treatment with propranolol during pregnancy should be further reevaluated in laboratory animals.