This systematic review was conducted as part of the U.S. Department of Agriculture and Department of Health and Human Services Pregnancy and Birth to 24 Months Project. The goal of this systematic review was to examine the following question: What is the relationship between never versus ever feeding human milk and food allergies, allergic rhinitis, atopic dermatitis, and asthma? This systematic review examines comparisons of infants who were never fed human milk with infants who were ever fed human milk (i.e., any amount of human milk feeding). was defined as feeding human milk alone or in combination with infant formula and/or complementary foods or beverages such as cow’s milk. was defined as mother’s own milk provided at the breast (i.e., nursing) or expressed and fed fresh or after refrigeration or freezing. Donor milk (e.g., banked milk) was not examined in this review. was defined as commercially-prepared infant formula meeting FDA and/or Codex Alimentarius international food standards. This systematic review examines available evidence related to food allergies, allergic rhinitis, and atopic dermatitis from birth through adulthood and asthma from childhood through adulthood (outcomes prior to childhood may represent transient recurrent wheeze).
Moderate evidence suggests that never, in comparison to ever, being fed human milk is associated with higher risk of childhood asthma. Limited evidence does not suggest a relationship between never versus ever being fed human milk and atopic dermatitis in childhood. Evidence about the relationship between never versus ever being fed human milk and atopic dermatitis from birth to 24 months is inconclusive, and there is insufficient evidence to determine the relationship of never versus ever being fed human milk with food allergies throughout the lifespan, allergic rhinitis throughout the lifespan, asthma in adolescence or in adulthood, and atopic dermatitis in adolescence or in adulthood. : Moderate – asthma in childhood; Limited – atopic dermatitis in childhood; Grade Not Assignable – food allergies, allergic rhinitis, atopic dermatitis outside of childhood, asthma in adolescence and adulthood.
The systematic review was conducted by a team of staff from the Nutrition Evidence Systematic Review in collaboration with a Technical Expert Collaborative. A single literature search was conducted to identify literature for several related systematic reviews that examined infant milk-feeding practices and different outcomes. The search was conducted in CINAHL, Cochrane, Embase, and PubMed, and used a search date range of January 1980 to March 2016. A manual search was done to identify articles that may not have been included in the electronic databases searched. Articles were screened independently by 2 NESR analysts to determine which articles met predetermined criteria for inclusion. Data from each included article were extracted, risks of bias were assessed, and both were checked for accuracy. The body of evidence was qualitatively synthesized, a conclusion statement was developed, and the strength of the evidence (grade) was assessed using pre-established criteria including evaluation of the internal validity/risk of bias, adequacy, consistency, impact, and generalizability of available evidence.
Forty-four articles met the inclusion criteria for this systematic review, including 5 with evidence about food allergies, 2 with evidence about allergic rhinitis, 24 with evidence about atopic dermatitis, and 22 with evidence about asthma. Almost all of the evidence was from observational studies. Evidence about the association between never versus ever feeding human milk and higher childhood asthma risk was moderate. Across the 17 independent studies (19 articles) that examined asthma in children, 9 found statistically significant associations, and all of them showed that never being fed human milk was associated with higher risk. The majority of nonsignificant associations were also consistent in suggesting higher risk of childhood asthma with never versus ever feeding human milk, and some of the inconsistency in statistical significance may be explained by insufficient statistical power. The ability to draw stronger conclusions was primarily limited by the limited statistical power in some studies and concerns about internal validity such as the potential for confounding in a body of evidence primarily made up of observational studies. Evidence about the lack of an association between never versus ever feeding human milk and atopic dermatitis in childhood was limited. Across the 9 studies that examined atopic dermatitis in children, the only significant association was from a study that used a sample in which about half of the participants were born small for gestational age (i.e., there was a concern about generalizability). The ability to draw stronger conclusions was limited by the small number of studies, limited statistical power in some studies, concerns with generalizability of the samples to diverse U.S. populations, and concern about the potential for reverse causality and confounding. Evidence about atopic dermatitis from birth to 24 months was inconclusive. Across 14 independent studies (16 articles), the associations were inconsistent in direction. There was also concern about the specificity of diagnosing atopic dermatitis in this age group. Evidence related to food allergies and allergic rhinitis throughout the lifespan and atopic dermatitis and asthma beyond childhood was scant.
