Maternal breastfeeding and autism spectrum disorder in children: A systematic review and meta-analysis

Objectives: Autism spectrum disorder (ASD) refers to a group of conditions variably affecting communicative and social interactive abilities presenting alongside behaviors with various restricted and repetitive patterns. In addition to genetic factors that influence the onset of the symptoms, there is growing interest in the potential involvement of non-genetic environmental factors. Some aspects of breastfeeding practices, including rates, timing, or optimality, have been put forward as environmental risk factors for autism. However, previous studies showed a controversial relationship between ASD and breastfeeding. Methods: A meta-analysis on the association between maternal breastfeeding and ASD in children was conducted. We also explored potential moderating factors which might influence this association. Articles reporting the association between breastfeeding and a diagnosis of ASD were included. Results: Seven articles were included in the meta-analysis. Cumulatively, children with ASD (n = 1463), either in the form of clinical diagnosis or self-report, were significantly less likely to have been breastfed than children without ASD (n = 1180) (OR = 0.61, 95% CI = 0.45-0.83, P = 0.002). Subgroup analyses revealed that results remained significant for children who were breastfed with additional supplementation. Discussion: This meta-analysis provides evidence that breastfeeding (exclusively or including additional supplements) may protect against ASD. Prospective longitudinal research is required to disentangle the complex relationships and to explore potential pathophysiological mechanisms.