Association between breastfeeding and the risk of autoimmune diseases: A systematic review and meta-analysis

Previous studies on the association between breastfeeding and autoimmune diseases risk have yielded inconsistent findings. This study employed a systematic review and meta-analysis to explore the effect of breastfeeding and its duration against autoimmune diseases.

Six databases (PubMed, Web of Science, Embase, CINAHL, Cochrane Library, PsycINFO) were systematically searched from inception to September 24, 2024. Studies on the association between breastfeeding and rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), ulcerative colitis (UC), Crohn's disease (CD), multiple sclerosis (MS) and type 1 diabetes mellitus (T1D) published within this period were included. Dichotomous outcome data from multiple studies were subjected to a random-effects meta-analysis using the Mantel-Haenszel method to estimate the pooled effect size. The Newcastle-Ottawa Scale was employed to evaluate quality.

Of the 40 included studies (35 case-control studies and 5 cohort studies), 12 were stratified by the duration of breastfeeding. The combined effect showed a protective association between breastfeeding and a reduced risk of autoimmune diseases (OR = 0.80; 95 %CI: 0.72 to 0.89; P < 0.001). This protective effect was significant for RA (OR = 0.66; 95 %CI: 0.46 to 0.93; P = 0.018), MS (OR = 0.78; 95 % CI: 0.63 to 0.98; P = 0.030) and T1D (OR = 0.80; 95 %CI: 0.66 to 0.98; P = 0.028), and was more pronounced with breastfeeding duration of at least four months (OR = 0.81; 95 %CI: 0.72 to 0.90; P < 0.001).

Breastfeeding provides an overall protective effect against autoimmune diseases and a significant protective effect on RA, MS and T1D. This protective effect appears stronger with breastfeeding duration of at least 4 months. These results highlight the necessity of promoting breastfeeding and supporting related policies to improve infant health.