Association of Maternal Lactation With Diabetes and Hypertension: A Systematic Review and Meta-analysis

IMPORTANCE: Lactation has been shown to be associated with lower rates of diabetes and hypertension in mothers. However, the strength of association has varied between studies, and sample sizes are relatively small. OBJECTIVE: To conduct a systematic review and meta-analysis to determine whether lactation is associated with a lower risk of diabetes and hypertension. DATA SOURCES: Ovid MEDLINE, Ovid Embase, Cochrane CENTRAL, and CINAHL databases were searched from inception to July 2018 with manual search of the references. STUDY SELECTION: Studies of adult women that specified duration of breastfeeding for at least 12 months, evaluated primary hypertension and diabetes as outcomes, were full-text articles in English, and reported statistical outcomes as odds ratios were included. DATA EXTRACTION AND SYNTHESIS: Study characteristics were independently extracted using a standard spreadsheet template and the data were pooled using the random-effects model. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline for reporting was followed. MAIN OUTCOMES AND MEASURES: Diabetes and hypertension. RESULTS: The search yielded 1558 articles, from which a total of 6 studies met inclusion criteria for association between breastfeeding and diabetes and/or hypertension. The 4 studies included in the meta-analysis for the association between lactation and diabetes had a total of 206 204 participants, and the 5 studies included in the meta-analysis for the association between lactation and hypertension had a total of 255 271 participants. Breastfeeding for more than 12 months was associated with a relative risk reduction of 30% for diabetes (pooled odds ratio, 0.70 [95% CI, 0.62-0.78]; P < .001) and a relative risk reduction of 13% for hypertension (pooled odds ratio, 0.87 [95% CI, 0.78-0.97]; P = .01). CONCLUSIONS AND RELEVANCE: This study suggests that education about the benefits of breastfeeding for prevention of diabetes and hypertension in women is a low-risk intervention that can be easily included in daily practice and may have a positive impact on cardiovascular outcomes in mothers.