Bisoprolol use seems to be increasing from the queries I receive. It is difficult to assess safety as published information relies on one study where the level in milk was undetectable BUT the baby was not given any of its mother’s milk. If other beta blockers are not suitable then the baby should be monitored closely for side effects and particularly hypo-glycaemia if newborn.
BNF ” With systemic use in the mother, infants should be monitored as there is a risk of possible toxicity due to beta-blockade. However, the amount of most beta-blockers present in milk is too small to affect infants.”