Diet during Pregnancy and Allergy Onset in the Childhood: A Systematic Literature Review and Meta-Analysis.

BACKGROUND: Maternal diet during pregnancy may influence childhood allergy risk. Our objective is to study the relationship between maternal diet during pregnancy and childhood's allergy onset. METHODS: We systematically search SCOPUS and PubMed (2014 to 2024) for randomized controlled trials (RCTs), case control, and cohorts investigating maternal diet during pregnancy and childhood allergy outcomes. The study protocol was registered in the PROSPERO (CRD42024570531). The evidence was critically appraised using Newcastle Ottawa Scale for case-control and cohort studies and Revised Cochrane risk of bias for cluster randomized trials (RoB2) tool for RCTs by two independent reviewers. Random-effects meta-analyses were performed to pool effect estimates, and heterogeneity was assessed using the I2 statistic. RESULTS: A total of 41 studies (37 cohorts, 1 case-control, and 3 RCTs) were analyzed. Meta-analyses suggest that maternal egg intake during pregnancy has a protective role on childhood eczema (OR: 0.51; 95% CI: 0.32, 0.80) and food allergy (OR: 0.60, 95% CI: 0.38, 0.96), and vitamin D has a negative association with childhood rhinitis (OR: 0.86; 95% CI: 0.76, 0.97). No significant association was found between maternal vitamin D intake on childhood asthma and fish oil supplementation on childhood hay fever and asthma. Variability in methodology, dietary assessment methods, and follow-up duration contributed to heterogeneity and becomes the limitation in our study. CONCLUSIONS: specific maternal diet patterns, such as egg and vitamin D consumption during pregnancy, may have help preventing childhood eczema, food allergy, and rhinitis. Further RCTs are needed to explore the effects of other dietary components on allergy outcomes.