Effect of propranolol on fetal tachycardia in diabetic pregnancy.

Propranolol was administered during the last 20 days of pregnancy to a diabetic woman because of fetal tachycardia (heart rate approximately 200 beats/min). With a daily dose of 160 mg of propranolol, a fetal heart rat of 120 to 160 beats/min could be achieved. Blood concentration of propranolol was measured in the mother and infant after birth. The level in the neonatal blood was 20 percent of the maternal sample, which is definitely higher than expected from animal experiments. No undersirable effect of propranolol treatment was detected. Postpartum, the infant demonstrated paroxysmal supraventricular tachycardia, and propranolol was again essential in maintaining a normal rate.