I have had many mothers (5) in the past year who wanted to take the day after pill. My answer was the same as for any birth control pill, which is hormones do pass into breastmilk but we do not know (yet?) of any effects on the nursing infant. Progesterone based birth control pills do not seem the affect milk composition or volume, but combination pills do. I also tell mothers that some Bmothers do take combination pills as birth control. All mothers I have talked to chose to take the day after pill, none of them reported any changes in milk volume or in baby's behavior (nursing most often or longer). Dany Gauthier IBCLC [log in to unmask] Tel: 514-923-3792 Fax:514-923-3802