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Population Health and Informed Feeding Decisions


Key Points

  • Breastfeeding is a women’s health issue. Disruption of breastfeeding is associated with higher rates of maternal breast and ovarian cancer, diabetes, hypertension, myocardial infarction, and stroke.

  • Breastfeeding is also a children’s health issue. Not being breastfed is associated with higher rates of infectious morbidity, childhood leukemia, sudden infant death syndrome, and necrotizing enterocolitis, as well as higher rates of obesity and diabetes and lower IQ.

  • On a population level, suboptimal breastfeeding is associated with substantial health costs, premature loss of life, and reduced cognitive development.

  • Most major medical organizations recommend 6 months of exclusive breastfeeding, with continued breastfeeding through 1 to 2 years or longer as mutually desired.

  • Informing families about the health importance of breastfeeding is necessary, but not sufficient, to affect infant feeding behavior.

  • Provider–patient communication can support breastfeeding by fostering relationships, validating emotions, sharing information and treatment recommendations, enabling self-management, and managing uncertainty.

  • It can be helpful to apply tenets of social cognitive theory, which considers both cognitive and environmental influences on behavior, to address the multiple factors that affect infant feeding.

  • Infant feeding decisions reflect multiple trade-offs that mothers negotiate to balance care for themselves and their infants. Efforts to make breastfeeding easier for mothers, as well as to promote health benefits, will enable more mothers and infants to breastfeed.

In human physiology, lactation follows pregnancy. Multiple studies have demonstrated that disruption of this physiology is associated with adverse outcomes for mothers and infants. For mothers, greater duration and intensity of lactation is associated with reduced risk for breast cancer, ovarian cancer, and cardiometabolic disease, among other health conditions. 1 For infants, breastfeeding is associated with reduced risk for infectious disease, autoimmune conditions, and sudden infant death syndrome (SIDS).

Sharing this information is an important part of anticipatory guidance in maternity care to enable families to make an informed decision regarding how to nourish and nurture the infant. This counseling is particularly important in light of aggressive and misleading marketing of infant formula. 2 Formula companies rely on disruption of breastfeeding to sell their product; every time a baby goes to breast, the formula industry loses a sale. 3 At the same time, individual mothers weigh multiple factors when deciding whether and how long to breastfeed, and patient-centered, respectful conversations that seek to understand her individual context are essential to support an informed decision.

Breastfeeding and Maternal Health

Although breastfeeding promotion typically has focused on the infant effects of ingesting human milk, lactation has substantial effects on maternal physiology, and these effects likely mediate associations between breastfeeding and women’s health.

Breast Cancer

The mammary gland does not completely differentiate until pregnancy and lactation have occurred. During puberty, exposure to estrogen and progesterone stimulates development of breast tissue, with elaboration of ducts and lobules with each menstrual cycle. During pregnancy, sustained exposure to estrogen and progesterone, as well as growth hormone, human placental lactogen, and prolactin, result in secretory differentiation, with the appearance of lactocytes that are capable of producing milk. 4 After birth, withdrawal of progesterone and stimulation of the breast by the infant prompt secretory activation and the production of mature milk. With weaning, the breast involutes and returns to its prepregnant state.

Completion of this differentiation may explain the reduced risk for breast cancer among women who have lactated for longer periods. In a meta-analysis that included more than 250,000 women, ever breastfeeding was associated with a lower risk for breast cancer (pooled odds ratio [OR], 0.78, 95% confidence interval [CI] 0.74 to 0.82). This association was particularly pronounced for luminal triple-negative breast cancers, 1 which have the highest mortality risk and which disproportionately affect black women. 5 In an analysis of the AMBER consortium, pregnancy without breastfeeding was associated with an increased risk for estrogen receptor–negative breast cancer among black women; each pregnancy without breastfeeding was associated with an increase in risk. 6 These findings underscore the urgency of dismantling structural barriers to breastfeeding for women of color.

Ovarian Cancer

Longer durations of breastfeeding are consistently associated with lower risk for ovarian cancer. 1 , 7 , 8 Several mechanisms have been proposed, including anovulation as a result of lactational amenorrhea and the effects of breastfeeding on gonadotropin homeostasis. 7 An immunologic mechanism also has been proposed, based on sensitization to MUC-1 antigen, which is present in breast epithelium and in ovarian cancer epithelium. Women who have breastfed have higher levels of anti–MUC-1 antibodies, with the highest levels found among women who have breastfed and have had mastitis, and higher levels of MUC-1 antibody are associated with lower ovarian cancer risk. 9 , 10

Cardiometabolic Disease

Breastfeeding imposes a substantial metabolic load on maternal physiology; exclusive breastfeeding requires 597 to 716 kcal (2.5 to 3.0 megajoule [MJ]) per day. 11 This metabolic demand may facilitate mobilization of gestational weight gain 12 and “reset” maternal metabolic changes of pregnancy. 13

The impact of lactation on weight trajectory is modified by maternal dietary intake, and in observational studies, associations between lactation and weight loss are inconsistent. A meta-analysis of 16 cohort studies including 47,655 women found insufficient evidence to conclude that breastfeeding per se increased postpartum weight loss. 1

However, greater breastfeeding duration and intensity is associated with reduced risk for type 2 diabetes and hypertension 1 and reduced risk for progression from gestational diabetes to type 2 diabetes. 14 Women with gestational diabetes who are breastfeeding at the time of their postpartum glucose tolerance test have lower glucose levels and are less likely to meet criteria for type 2 diabetes. 15 , 16 These associations may reflect the effects of lactation on maternal physiology or the extent to which underlying maternal insulin resistance is associated with early weaning. 17

Longer breastfeeding is similarly associated with reduced hypertension risk 1 , 18 and reduced risk for myocardial infarction, 19 cardiovascular disease, 20 and stroke. 21 These findings suggest that enabling breastfeeding is an essential part of improving women’s cardiovascular health.

Depression

Although it is conventional wisdom that breastfeeding prevents depression, the relationship between breastfeeding and maternal mood is complex. Systematic reviews of the literature have found that prenatal depression and anxiety are risk factors for early weaning, and breastfeeding difficulties often presage or co-present with mood disorders. 22 , 23

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