pediatrics
March 2012, VOLUME129 /ISSUE 3

# Breastfeeding and the Use of Human Milk

1. SECTION ON BREASTFEEDING

## Abstract

Breastfeeding and human milk are the normative standards for infant feeding and nutrition. Given the documented short- and long-term medical and neurodevelopmental advantages of breastfeeding, infant nutrition should be considered a public health issue and not only a lifestyle choice. The American Academy of Pediatrics reaffirms its recommendation of exclusive breastfeeding for about 6 months, followed by continued breastfeeding as complementary foods are introduced, with continuation of breastfeeding for 1 year or longer as mutually desired by mother and infant. Medical contraindications to breastfeeding are rare. Infant growth should be monitored with the World Health Organization (WHO) Growth Curve Standards to avoid mislabeling infants as underweight or failing to thrive. Hospital routines to encourage and support the initiation and sustaining of exclusive breastfeeding should be based on the American Academy of Pediatrics-endorsed WHO/UNICEF “Ten Steps to Successful Breastfeeding.” National strategies supported by the US Surgeon General’s Call to Action, the Centers for Disease Control and Prevention, and The Joint Commission are involved to facilitate breastfeeding practices in US hospitals and communities. Pediatricians play a critical role in their practices and communities as advocates of breastfeeding and thus should be knowledgeable about the health risks of not breastfeeding, the economic benefits to society of breastfeeding, and the techniques for managing and supporting the breastfeeding dyad. The “Business Case for Breastfeeding” details how mothers can maintain lactation in the workplace and the benefits to employers who facilitate this practice.

KEY WORDS
• breastfeeding
• complementary foods
• infant nutrition
• lactation
• human milk
• nursing
1. Abbreviations:
AAP
AHRQ
Agency for Healthcare Research and Quality
CDC
Centers for Disease Control and Prevention
CI
confidence interval
CMV
cytomegalovirus
DHA
docosahexaenoic acid
NEC
necrotizing enterocolitis
OR
odds ratio
SIDS
sudden infant death syndrome
WHO
World Health Organization
2. ## Introduction

Six years have transpired since publication of the last policy statement of the American Academy of Pediatrics (AAP) regarding breastfeeding.1 Recently published research and systematic reviews have reinforced the conclusion that breastfeeding and human milk are the reference normative standards for infant feeding and nutrition. The current statement updates the evidence for this conclusion and serves as a basis for AAP publications that detail breastfeeding management and infant nutrition, including the AAP Breastfeeding Handbook for Physicians,2AAP Sample Hospital Breastfeeding Policy for Newborns,3AAP Breastfeeding Residency Curriculum,4 and the AAP Safe and Healthy Beginnings Toolkit.5 The AAP reaffirms its recommendation of exclusive breastfeeding for about 6 months, followed by continued breastfeeding as complementary foods are introduced, with continuation of breastfeeding for 1 year or longer as mutually desired by mother and infant.

## Epidemiology

Information regarding breastfeeding rates and practices in the United States is available from a variety of government data sets, including the Centers for Disease Control and Prevention (CDC) National Immunization Survey,6 the NHANES,7 and Maternity Practices and Infant Nutrition and Care.8 Drawing on these data and others, the CDC has published the “Breastfeeding Report Card,” which highlights the degree of progress in achieving the breastfeeding goals of the Healthy People 2010 targets as well as the 2020 targets (Table 1).911

TABLE 1

Healthy People Targets 2010 and 2020(%)

The rate of initiation of breastfeeding for the total US population based on the latest National Immunization Survey data are 75%.11 This overall rate, however, obscures clinically significant sociodemographic and cultural differences. For example, the breastfeeding initiation rate for the Hispanic or Latino population was 80.6%, but for the non-Hispanic black or African American population, it was 58.1%. Among low-income mothers (participants in the Special Supplemental Nutrition Program for Women, Infants, and Children [WIC]), the breastfeeding initiation rate was 67.5%, but in those with a higher income ineligible for WIC, it was 84.6%.12 Breastfeeding initiation rate was 37% for low-income non-Hispanic black mothers.7 Similar disparities are age-related; mothers younger than 20 years initiated breastfeeding at a rate of 59.7% compared with the rate of 79.3% in mothers older than 30 years. The lowest rates of initiation were seen among non-Hispanic black mothers younger than 20 years, in whom the breastfeeding initiation rate was 30%.7

Although over the past decade, there has been a modest increase in the rate of “any breastfeeding” at 3 and 6 months, in none of the subgroups have the Healthy People 2010 targets been reached. For example, the 6-month “any breastfeeding” rate for the total US population was 43%, the rate for the Hispanic or Latino subgroup was 46%, and the rate for the non-Hispanic black or African American subgroup was only 27.5%. Rates of exclusive breastfeeding are further from Healthy People 2010 targets, with only 13% of the US population meeting the recommendation to breastfeed exclusively for 6 months. Thus, it appears that although the breastfeeding initiation rates have approached the 2010 Healthy People targets, the targets for duration of any breastfeeding and exclusive breastfeeding have not been met.

Furthermore, 24% of maternity services provide supplements of commercial infant formula as a general practice in the first 48 hours after birth. These observations have led to the conclusion that the disparities in breastfeeding rates are also associated with variations in hospital routines, independent of the populations served. As such, it is clear that greater emphasis needs to be placed on improving and standardizing hospital-based practices to realize the newer 2020 targets (Table 1).

## Infant Outcomes

### Methodologic Issues

Breastfeeding results in improved infant and maternal health outcomes in both the industrialized and developing world. Major methodologic issues have been raised as to the quality of some of these studies, especially as to the size of the study populations, quality of the data set, inadequate adjustment for confounders, absence of distinguishing between “any” or “exclusive” breastfeeding, and lack of a defined causal relationship between breastfeeding and the specific outcome. In addition, there are inherent practical and ethical issues that have precluded prospective randomized interventional trials of different feeding regimens. As such, the majority of published reports are observational cohort studies and systematic reviews/meta-analyses.

To date, the most comprehensive publication that reviews and analyzes the published scientific literature that compares breastfeeding and commercial infant formula feeding as to health outcomes is the report prepared by the Evidence-based Practice Centers of the Agency for Healthcare Research and Quality (AHRQ) of the US Department of Health Human Services titled Breastfeeding and Maternal and Infant Health Outcomes in Developed Countries.13 The following sections summarize and update the AHRQ meta-analyses and provide an expanded analysis regarding health outcomes. Table 2 summarizes the dose-response relationship between the duration of breastfeeding and its protective effect.

TABLE 2

Dose-Response Benefits of Breastfeedinga

### Respiratory Tract Infections and Otitis Media

The risk of hospitalization for lower respiratory tract infections in the first year is reduced 72% if infants breastfed exclusively for more than 4 months.13,14 Infants who exclusively breastfed for 4 to 6 months had a fourfold increase in the risk of pneumonia compared with infants who exclusively breastfed for more than 6 months.15 The severity (duration of hospitalization and oxygen requirements) of respiratory syncytial virus bronchiolitis is reduced by 74% in infants who breastfed exclusively for 4 months compared with infants who never or only partially breastfed.16

Any breastfeeding compared with exclusive commercial infant formula feeding will reduce the incidence of otitis media (OM) by 23%.13 Exclusive breastfeeding for more than 3 months reduces the risk of otitis media by 50%. Serious colds and ear and throat infections were reduced by 63% in infants who exclusively breastfed for 6 months.17

### Gastrointestinal Tract Infections

Any breastfeeding is associated with a 64% reduction in the incidence of nonspecific gastrointestinal tract infections, and this effect lasts for 2 months after cessation of breastfeeding.13,14,17,18

### Necrotizing Enterocolitis

Meta-analyses of 4 randomized clinical trials performed over the period 1983 to 2005 support the conclusion that feeding preterm infants human milk is associated with a significant reduction (58%) in the incidence of necrotizing enterocolitis (NEC).13 A more recent study of preterm infants fed an exclusive human milk diet compared with those fed human milk supplemented with cow-milk-based infant formula products noted a 77% reduction in NEC.19 One case of NEC could be prevented if 10 infants received an exclusive human milk diet, and 1 case of NEC requiring surgery or resulting in death could be prevented if 8 infants received an exclusive human milk diet.19

### Sudden Infant Death Syndrome and Infant Mortality

Meta-analyses with a clear definition of degree of breastfeeding and adjusted for confounders and other known risks for sudden infant death syndrome (SIDS) note that breastfeeding is associated with a 36% reduced risk of SIDS.13 Latest data comparing any versus exclusive breastfeeding reveal that for any breastfeeding, the multivariate odds ratio (OR) is 0.55 (95% confidence interval [CI], 0.44–0.69). When computed for exclusive breastfeeding, the OR is 0.27 (95% CI, 0.27–0.31).20 A proportion (21%) of the US infant mortality has been attributed, in part, to the increased rate of SIDS in infants who were never breastfed.21 That the positive effect of breastfeeding on SIDS rates is independent of sleep position was confirmed in a large case-control study of supine-sleeping infants.22,23

It has been calculated that more than 900 infant lives per year may be saved in the United States if 90% of mothers exclusively breastfed for 6 months.24 In the 42 developing countries in which 90% of the world’s childhood deaths occur, exclusive breastfeeding for 6 months and weaning after 1 year is the most effective intervention, with the potential of preventing more than 1 million infant deaths per year, equal to preventing 13% of the world’s childhood mortality.25

### Allergic Disease

There is a protective effect of exclusive breastfeeding for 3 to 4 months in reducing the incidence of clinical asthma, atopic dermatitis, and eczema by 27% in a low-risk population and up to 42% in infants with positive family history.13,26 There are conflicting studies that examine the timing of adding complementary foods after 4 months and the risk of allergy, including food allergies, atopic dermatitis, and asthma, in either the allergy-prone or nonatopic individual.26 Similarly, there are no convincing data that delaying introduction of potentially allergenic foods after 6 months has any protective effect.2730 One problem in analyzing this research is the low prevalence of exclusive breastfeeding at 6 months in the study populations. Thus, research outcomes in studies that examine the development of atopy and the timing of introducing solid foods in partially breastfed infants may not be applicable to exclusively breastfed infants.

### Celiac Disease

There is a reduction of 52% in the risk of developing celiac disease in infants who were breastfed at the time of gluten exposure.31 Overall, there is an association between increased duration of breastfeeding and reduced risk of celiac disease when measured as the presence of celiac antibodies. The critical protective factor appears to be not the timing of the gluten exposure but the overlap of breastfeeding at the time of the initial gluten ingestion. Thus, gluten-containing foods should be introduced while the infant is receiving only breast milk and not infant formula or other bovine milk products.

### Inflammatory Bowel Disease

Breastfeeding is associated with a 31% reduction in the risk of childhood inflammatory bowel disease.32 The protective effect is hypothesized to result from the interaction of the immunomodulating effect of human milk and the underlying genetic susceptibility of the infant. Different patterns of intestinal colonization in breastfed versus commercial infant formula–fed infants may add to the preventive effect of human milk.33

### Obesity

Because rates of obesity are significantly lower in breastfed infants, national campaigns to prevent obesity begin with breastfeeding support.34,35 Although complex factors confound studies of obesity, there is a 15% to 30% reduction in adolescent and adult obesity rates if any breastfeeding occurred in infancy compared with no breastfeeding.13,36 The Framingham Offspring study noted a relationship of breastfeeding and a lower BMI and higher high-density lipoprotein concentration in adults.37 A sibling difference model study noted that the breastfed sibling weighed 14 pounds less than the sibling fed commercial infant formula and was less likely to reach BMI obesity threshold.38 The duration of breastfeeding also is inversely related to the risk of overweight; each month of breastfeeding being associated with a 4% reduction in risk.14

The interpretation of these data is confounded by the lack of a definition in many studies of whether human milk was given by breastfeeding or by bottle. This is of particular importance, because breastfed infants self-regulate intake volume irrespective of maneuvers that increase available milk volume, and the early programming of self-regulation, in turn, affects adult weight gain.39 This concept is further supported by the observations that infants who are fed by bottle, formula, or expressed breast milk will have increased bottle emptying, poorer self-regulation, and excessive weight gain in late infancy (older than 6 months) compared with infants who only nurse from the breast.40,41

### Diabetes

Up to a 30% reduction in the incidence of type 1 diabetes mellitus is reported for infants who exclusively breastfed for at least 3 months, thus avoiding exposure to cow milk protein.13,42 It has been postulated that the putative mechanism in the development of type 1 diabetes mellitus is the infant’s exposure to cow milk β-lactoglobulin, which stimulates an immune-mediated process cross-reacting with pancreatic β cells. A reduction of 40% in the incidence of type 2 diabetes mellitus is reported, possibly reflecting the long-term positive effect of breastfeeding on weight control and feeding self-regulation.43

### Childhood Leukemia and Lymphoma

There is a reduction in leukemia that is correlated with the duration of breastfeeding.14,44 A reduction of 20% in the risk of acute lymphocytic leukemia and 15% in the risk of acute myeloid leukemia in infants breastfed for 6 months or longer.45,46 Breastfeeding for less than 6 months is protective but of less magnitude (approximately 12% and 10%, respectively). The question of whether the protective effect of breastfeeding is a direct mechanism of human milk on malignancies or secondarily mediated by its reduction of early childhood infections has yet to be answered.

### Neurodevelopmental Outcomes

Consistent differences in neurodevelopmental outcome between breastfed and commercial infant formula–fed infants have been reported, but the outcomes are confounded by differences in parental education, intelligence, home environment, and socioeconomic status.13,47 The large, randomized Promotion of Breastfeeding Intervention Trial provided evidence that adjusted outcomes of intelligence scores and teacher’s ratings are significantly greater in breastfed infants.4850 In addition, higher intelligence scores are noted in infants who exclusively breastfed for 3 months or longer, and higher teacher ratings were observed if exclusive breastfeeding was practiced for 3 months or longer. Significantly positive effects of human milk feeding on long-term neurodevelopment are observed in preterm infants, the population more at risk for these adverse neurodevelopmental outcomes.5154

## Preterm Infants

There are several significant short- and long-term beneficial effects of feeding preterm infants human milk. Lower rates of sepsis and NEC indicate that human milk contributes to the development of the preterm infant’s immature host defense.19,5559 The benefits of feeding human milk to preterm infants are realized not only in the NICU but also in the fewer hospital readmissions for illness in the year after NICU discharge.51,52 Furthermore, the implications for a reduction in incidence of NEC include not only lower mortality rates but also lower long-term growth failure and neurodevelopmental disabilities.60,61 Clinical feeding tolerance is improved, and the attainment of full enteral feeding is hastened by a diet of human milk.51,52,59

Neurodevelopmental outcomes are improved by the feeding of human milk. Long-term studies at 8 years of age through adolescence suggest that intelligence test results and white matter and total brain volumes are greater in subjects who had received human milk as infants in the NICU.53,54 Extremely preterm infants receiving the greatest proportion of human milk in the NICU had significantly greater scores for mental, motor, and behavior ratings at ages 18 months and 30 months.51,52 These data remain significant after adjustment for confounding factors, such as maternal age, education, marital status, race, and infant morbidities. These neurodevelopmental outcomes are associated with predominant and not necessarily exclusive human milk feeding. Human milk feeding in the NICU also is associated with lower rates of severe retinopathy of prematurity.62,63 Long-term studies of preterm infants also suggest that human milk feeding is associated with lower rates of metabolic syndrome, and in adolescents, it is associated with lower blood pressures and low-density lipoprotein concentrations and improved leptin and insulin metabolism.64,65

The potent benefits of human milk are such that all preterm infants should receive human milk (Table 3). Mother’s own milk, fresh or frozen, should be the primary diet, and it should be fortified appropriately for the infant born weighing less than 1.5 kg. If mother’s own milk is unavailable despite significant lactation support, pasteurized donor milk should be used.19,66 Quality control of pasteurized donor milk is important and should be monitored. New data suggest that mother’s own milk can be stored at refrigerator temperature (4°C) in the NICU for as long as 96 hours.67 Data on thawing, warming, and prolonged storage need updating. Practices should involve protocols that prevent misadministration of milk.

TABLE 3

Recommendations on Breastfeeding Management for Preterm Infants

## Maternal Outcomes

Both short- and long-term health benefits accrue to mothers who breastfeed. Such mothers have decreased postpartum blood loss and more rapid involution of the uterus. Continued breastfeeding leads to increased child spacing secondary to lactational amenorrhea. Prospective cohort studies have noted an increase in postpartum depression in mothers who do not breastfeed or who wean early.68 A large prospective study on child abuse and neglect perpetuated by mothers found, after correcting for potential confounders, that the rate of abuse/neglect was significantly increased for mothers who did not breastfeed as opposed to those who did (OR: 2.6; 95% CI: 1.7–3.9).69

Studies of the overall effect of breastfeeding on the return of the mothers to their pre-pregnancy weight are inconclusive, given the large numbers of confounding factors on weight loss (diet, activity, baseline BMI, ethnicity).13 In a covariate-adjusted study of more than 14 000 women postpartum, mothers who exclusively breastfed for longer than 6 months weighed 1.38 kg less than those who did not breastfeed.70 In mothers without a history of gestational diabetes, breastfeeding duration was associated with a decreased risk of type 2 diabetes mellitus; for each year of breastfeeding, there was a decreased risk of 4% to 12%.71,72 No beneficial effect for breastfeeding was noted in mothers who were diagnosed with gestational diabetes.

The longitudinal Nurses Health Study noted an inverse relationship between the cumulative lifetime duration of breastfeeding and the development of rheumatoid arthritis.73 If cumulative duration of breastfeeding exceeded 12 months, the relative risk of rheumatoid arthritis was 0.8 (95% CI: 0.8–1.0), and if the cumulative duration of breastfeeding was longer than 24 months, the relative risk of rheumatoid arthritis was 0.5 (95% CI: 0.3–0.8).73 An association between cumulative lactation experience and the incidence of adult cardiovascular disease was reported by the Women’s Health Initiative in a longitudinal study of more than 139 000 postmenopausal women.74 Women with a cumulative lactation history of 12 to 23 months had a significant reduction in hypertension (OR: 0.89; 95% CI: 0.84–0.93), hyperlipidemia (OR: 0.81; 95% CI: 0.76–0.87), cardiovascular disease (OR: 0.90; 95% CI: 0.85–0.96), and diabetes (OR: 0.74; 95% CI: 0.65–0.84).

Cumulative lactation experience also correlates with a reduction in both breast (primarily premenopausal) and ovarian cancer.13,14,75 Cumulative duration of breastfeeding of longer than 12 months is associated with a 28% decrease in breast cancer (OR: 0.72; 95% CI: 0.65–0.8) and ovarian cancer (OR: 0.72; 95% CI: 0.54–0.97).76 Each year of breastfeeding has been calculated to result in a 4.3% reduction in breast cancer.76,77

## Conclusions

Research and practice in the 5 years since publication of the last AAP policy statement have reinforced the conclusion that breastfeeding and the use of human milk confer unique nutritional and nonnutritional benefits to the infant and the mother and, in turn, optimize infant, child, and adult health as well as child growth and development. Recently, published evidence-based studies have confirmed and quantitated the risks of not breastfeeding. Thus, infant feeding should not be considered as a lifestyle choice but rather as a basic health issue. As such, the pediatrician’s role in advocating and supporting proper breastfeeding practices is essential and vital for the achievement of this preferred public health goal.35

Arthur I. Eidelman, MD

Richard J. Schanler, MD

## Section on Breastfeeding Executive Committee, 2011–2012

Margreete Johnston, MD

Susan Landers, MD

Larry Noble, MD

Kinga Szucs, MD

Laura Viehmann, MD

## Past Contributing Executive Committee Members

Lori Feldman-Winter, MD

Ruth Lawrence, MD

## Staff

Sunnah Kim, MS

Ngozi Onyema, MPH

## Footnotes

• This document is copyrighted and is property of the American Academy of Pediatrics and its Board of Directors. All authors have filed conflict of interest statements with the American Academy of Pediatrics. Any conflicts have been resolved through a process approved by the Board of Directors. The American Academy of Pediatrics has neither solicited nor accepted any commercial involvement in the development of the content of this publication.

• All policy statements from the American Academy of Pediatrics automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.