Birth control for women who are breastfeeding is important worldwide. Each year, millions of women decide whether to use birth control after having a baby. The decision includes the type of birth control and when to start using it. Researchers and health care providers debate these issues. Some people worry that hormones could affect the breast milk and the baby. Ideally, the birth control would not affect the type or amount of breast milk. The best time for starting birth control is also important. It is hard to know when monthly cycles will return and when the woman could get pregnant again.
Combined birth control methods have the hormones estrogen and progestin. Other types of birth control have only progestin or no hormones. This review looked at whether combined birth control affects breastfeeding more than other kinds of birth control. We did computer searches for randomized trials of birth control used during breastfeeding. Combined hormonal methods were compared with another hormonal one or a 'dummy' method. In addition, we looked at reference lists to find trials. We also wrote to researchers to find more studies.
We found five studies that varied in quality. Some trials lost many women during the study. Two reports compared birth control pills to a 'dummy' and they had different results. Another study found that progestin-only did not affect breast milk. One trial found less breast milk produced with combined birth control. That study also lost many of the women, though. We found no major difference in infant growth or weight due to these types of birth control.
The results did not show whether hormonal birth control affects breast milk or the baby. At least one good randomized trial is needed to address these issues. Right now, information is too limited to say whether breastfeeding women should use hormonal birth control or not.