Fetal heart rate response to a controlled sound stimulus after propranolol administration to the mother

The fetal heart rate response to a controlled sound stimulus was recorded in 36 pregnant women before and after a maternal peroral dose of either 80 mg propranolol, or placebo. The sound stimulation was repeated 60 minutes, 120 minutes and 180 minutes after the drug administration. The fetal heart rate response to sound was significantly depressed by this moderate dose of propranolol. The sound stimulation method is found to reflect sensitively the immediate influence of propranolol on the fetus.