Propranolol in pregnancy three year prospective study.

We compared propranolol with methyldopa in a randomized prospective study of 28 women with pregnancy associated hypertension. Both drugs were equally effective in controlling maternal hypertension. There was no significant difference in the birthweights of the babies in each group. However one infant born to a mother receiving propranolol had symptomatic hypoglycaemia. The mean peak levels of propranolol, propranolol glucuronide, 4-hydroxypropranolol, and 4-hydroxypropranolol glucuronide were not significantly different in the first, second, third trimesters and at least 3 months post partum. The mean peak plasma level of naphthoxylactic acid however was significantly less in the third trimester compared with post partum levels. Propranolol and its metabolites were found to cross into breast milk with the maximum dose likely to be ingested by the infant as either propranolol or propranolol glucuronide being 7 micrograms of propranolol per 100 g of breast milk, being approximately 0.1% of the maternal dose.