Association of breastfeeding status with risk of autism spectrum disorder: A systematic review, dose-response analysis and meta-analysis

Current evidence indicates that nutritional status in newborns, especially the duration of breastfeeding, plays a key role in the pathogenesis of autism spectrum disorder. We aimed to systematically review and meta-analyze relevant studies with findings of an association between autism spectrum disorder and breastfeeding patterns, and undertook an extensive dose-response analysis to interpret the results more accurately. Ten electronic databases and manual search of reference lists were used to identify relevant studies in September 2018. Dose-response and conventional meta-analysis were conducted by the random-effects model. The study protocol was registered in PROSPERO with CRD42016043128. Seven case-control studies were found in which the association between ever breastfeeding and risk of autism spectrum disorder was investigated. We found a 58 % decrease in the risk of autism spectrum disorder with ever breastfeeding and a 76 % decrease in the risk with exclusive breastfeeding. According to our dose-response meta-analysis, breastfeeding for 6 months was associated with a 54 % reduction in the risk. In the conventional meta-analysis, breastfeeding for 12–24 months was associated with the most significant reduction in the risk of autism spectrum disorder. Our results highlight the importance of breastfeeding to decrease the risk of autism spectrum disorder.