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 shorter versus longer durations of any human milk feeding and cardiovascular disease outcomes in offspring? This systematic review examines comparisons of infants who were fed human milk for shorter durations with infants who were fed human milk for longer durations. 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. This systematic review examines available evidence related to cardiovascular disease outcomes in offspring from childhood through adulthood, including blood lipids, blood pressure, arterial stiffness, metabolic syndrome, cardiovascular disease, and cardiovascular disease-related mortality.
Moderate evidence suggests that there is no association between the duration of any human milk feeding and blood pressure in childhood. Evidence about the relationship of shorter versus longer durations of any human milk feeding with blood lipids in childhood and adulthood and with metabolic syndrome was inconclusive, and there was insufficient evidence to determine the relationship of shorter versus longer durations of any human milk feeding with endpoint cardiovascular disease outcomes, blood pressure in adolescence or adulthood, blood lipids in adolescence, and arterial stiffness. Moderate – blood pressure in childhood; Grade Not Assignable – cardiovascular disease, cardiovascular disease-related mortality, blood lipids, blood pressure in adolescence or adulthood, arterial stiffness, metabolic syndrome.
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.
Twenty-four articles met the inclusion criteria for this systematic review, including 13 with evidence about blood pressure, 10 with evidence about blood lipids, 3 with evidence about metabolic syndrome, 3 with evidence about arterial stiffness, and 2 with evidence about cardiovascular disease-related mortality (some articles included evidence for more than one outcome). Evidence about the lack of an association between shorter versus longer durations of any human milk feeding and blood pressure in childhood was moderate. Compelling evidence from the Promotion of Breastfeeding Intervention Trial showed no significant relationship between the duration of any human milk feeding and blood pressure at 6.5 or 11.5 years of age, and inconsistent evidence across 6 independent prospective cohort studies did not suggest any discernable relationship between the duration of any human milk feeding and blood pressure in childhood. The ability to draw stronger conclusions was primarily limited by the small number of studies and concern about generalizability of the evidence, because none of the evidence was from the U.S. and U.S. populations may be at higher risk for cardiovascular disease than the populations examined by the studies included in the systematic review. Evidence about blood lipids in childhood and adulthood and about metabolic syndrome was inconclusive, primarily due to inconsistencies in the direction and statistical significance of the findings. Evidence related to outcomes beyond childhood was scant, and only 2 articles, with evidence from the same retrospective cohort study, examined endpoint cardiovascular disease outcomes (cardiovascular disease-related mortality in both articles).
