Combined birth control pills with both estrogen and progestin hormones have caused some mothers not to make enough milk. Your doctor may suggest using other methods of birth control during this time because it is highly possible to get pregnant while you are breastfeeding. Smoking is terrible for the health of the baby, regardless of whether or not the mother breastfeeds. The nicotine that is transmitted through the breast milk can cause babies to have gas or be fussy. It may also impede milk production.
Alcohol goes through the milk to the baby.
Breastfeeding mothers should have no more than one beer, one glass of wine or one mixed drink in a day. If you do decide to drink, drink only just after breastfeeding. At no time, should a breastfeeding mother take any illegal or controlled substances. La Leche is an international, nonprofit, nonsectarian organization dedicated to providing education, information, support, and encouragement to women who want to breastfeed. This site includes a variety of information on breastfeeding, including frequently asked questions about breastfeeding and a link to periodical articles on this subject.