Hormonal contraception and lactation.J Hum Lact. 1996 Dec; 12(4):315-8.JH
Hormonal contraceptive measures can be used immediately postpartum if the patient so desires. Progestin-only contraceptives are preferable to estrogen-containing methods if initiated during the first six months after delivery. Progestin only contraceptives do not appear to affect milk volume, composition, or to cause deleterious effects in the infant. Ideally for women who desire a form of contraception in addition to lactation-induced amenorrhea, progestin-only methods should be started at six weeks postpartum if the woman is fully breastfeeding. Since contraception protection is provided by lactation amenorrhea, the six week delay will decrease infant exposure to exogenous hormones and decrease the incidence of irregular postpartum bleeding. Milk volume may decrease with the use of estrogen; however, no detrimental effects have been shown on infant growth or development. For women who are planning to gradually wean their infant, use of COCs may provide an easier transition to bottle-feeding. COCs should be used with caution by women who are not able to obtain supplemental milk. A decrease in milk volume can lead to earlier discontinuation of the hormonal contraceptive in an attempt to increase milk quantity. Supplementation is often needed, and then the woman ovulates again, possibly resulting in an unintended pregnancy. Many women are motivated immediately postpartum to accept contraception. For other women, lack of access to health care may provide barriers in obtaining adequate contraception later. In either case, there are adequate data to show no detriments of starting progestin-only contraceptives within days of delivery. Therefore, the best method for the patient should be employed to ensure adequate contraception while preserving optimal lactation.