Breast-feeding and Contraception

Abstract

Emphasis on the advantages of breast-feeding to the infant and to the nursing mother has been accompanied by resurgent interest in this practice. Although breast-feeding has many desirable features, the needs of the lactating mother and her nursing infant may not always be complementary. Possible competition between the mother's requirement for adequate contraception and the infant's nutrition or maturation is an important example. For this reason, the relationship between breast-feeding and various forms of contraception has been reviewed. LACTATIONAL AMENORRHEA Nursing mothers experience lactational amenorrhea of longer duration than postpartum amenorrhea of women who do not breast-feed their infants.1-3 In addition to a decline in maternal estrogen levels following delivery, hyperprolactinemia— enhanced by suckling—facilitiates the onset of breast milk production.4,5 Depending to some extent on the frequency of breast-feeding, modestly raised prolactin levels may be maintained for several or many months post partum.4,6-8 Many studies suggest that prolactin exerts antagonistic effects on the secretion and actions of gonadotropins, and lactational amenorrhea seems to parallel the presence of hyperprolactinemia.7,8 As breast-feeding continues, the prolactin levels usually return to normal, with some episodic increases occurring in response to suckling. The contraceptive action provided by breast-feeding alone is well established. When breast-feeding is used exclusively and amenorrhea exists, ovulation usually does not occur before the end of the tenth postpartum week.3 However, this contraceptive effect is not universal; 5% to 10% of women with lactational amenorrhea become pregnant, and an even greater proportion of nursing mothers who have reinitiated menstruation become pregnant.2,9 These data indicate that women who want to breast-feed and also avoid pregnancy need to use contraception for complete protection, beginning about four to five weeks post partum when breast-feeding is firmly established.9