Objectives: To summarize the current evidence on the association between maternal breastfeeding and the occurrence of attention deficit/hyperactivity disorder (ADHD) in offspring. Methods: We searched for studies published in English before May 2018 using the PubMed, EMBASE, Cochrane, and Web of Science databases. We included cohort studies, case-control studies, and cross-sectional studies, that focused on the association between maternal breastfeeding and the occurrence of ADHD in offspring. Random effects models were used for combined analyses. Results: Two cohort studies, 7 case-control studies and 3 cross-sectional studies, with 3,686 cases and 106,907 participants, were included. Children with any maternal breastfeeding had a lower incidence of ADHD than children who were never breastfed (odds ratio [OR]: 0.70; 95% confidence interval [CI]:0.52-0.93). Further analyses also showed associations between reduced ADHD incidence and duration of breastfeeding. Children breastfed for over 1 month, over 3 months, over 6 months, and over 12 months had a lower incidence of ADHD than children breastfed for less than 1 month (OR: 0.20; 95% CI: 0.11-0.38), less than 3 months (OR: 0.33; 95% CI: 0.23-0.47), less than 6 months (OR: 0.50; 95% CI: 0.41-0.61), and less than 12 months (OR: 0.55; 95% CI: 0.37-0.81), respectively. These results were stable in the 1-month, 3-month, and 6-month breastfeeding groups. Conclusion: With our meta-analysis, we provide evidence that maternal breastfeeding may reduce the risk of ADHD in children. The causality of this relationship and underlying mechanisms need to be explored in future prospective studies.
Keywords: Attention deficit/hyperactivity disorder; breastfeeding; meta-analysis; nutrition; protective factor.