Effects on baby: There have been no adverse reports of side effects to the baby. Both progestin and estrogen are approved by the AAP for use by nursing moms. Children whose mothers used hormonal birth control while nursing have been followed as late as 17 years of age. The exception to this is the very young baby - less than 6 weeks old. There may be some concern about the baby's immature liver being able to metabolize the hormones passed through the milk well enough.
Any hormonal birth control may cause fussiness in the baby (not reported in the literature but often anecdotally by mothers). This may be due to the hormones causing a minimal decrease in the protein/nitrogen/lactose content of the milk. Some mothers have reported marked improvement in their baby's degree of fussiness once they come off hormonal birth control.
Effects on mother: If you had gestational diabetes during pregnancy, talk to your doctor about the safety of using the mini-pill while breastfeeding. A 1998 study conducted at the University of Southern California School of Medicine in Los Angeles (Kjos SL, et al. Contraception and the risk of type 2 diabetes mellitus in Latina women with prior gestational diabetes mellitus. JAMA. 1998 Aug 12;280(6):533-8.) indicated that for certain women, taking the mini-pill while breastfeeding may increase the risk of chronic, non-insulin-dependent diabetes. This study of more than 900 Latinas found that those who had been diagnosed with gestational diabetes and then took mini-pills while breastfeeding had an almost threefold risk of developing type II diabetes within a year, compared with those who used different contraception. This study concentrated on Hispanic women, and thus it is not clear whether the results can be applied to all ethnic groups. Other, smaller studies on the mini-pill did not show any increased rates of diabetes, so more research in needed on this subject.
