Impact of breastfeeding during infancy on functional constipation at 3 years of age: the Japan Environment and Children’s Study

BACKGROUND: There is a lack of large, nationwide, birth cohort studies in Japan that examine the relationships of initial feeding habits and breastfeeding period duration with offspring functional constipation at 3 years of age. This study assessed the impact of breastfeeding during infancy on early childhood functional constipation. METHODS: The fixed data of 70,078 singleton births from the ongoing Japan Environment and Children’s Study cohort study that commenced in 2011 were used to identify functional constipation as estimated by Rome III at 3 years of age. The exposure variables were breastfeeding period duration until 12 months of age (never, up to 6 months, or ≥ 7 months) as well as breastfeeding status at 1 month and 6 months of age (breastfeeding exclusively, partial breastfeeding, or infant formula feeding only). Multiple logistic regression analysis was employed to search for correlations for functional constipation development with breastfeeding period duration until 12 months of age and breastfeeding status during infancy. RESULTS: We identified 8,118 toddlers (11.6%) who met the Rome III criteria at 3 years of age. After controlling for potential covariates, a breastfeeding period duration of 7 months or more was inversely related to functional constipation development (≥ 7 months: adjusted odds ratio [OR] [95% confidence interval (CI)] 0.76 [0.65, 0.88] versus never breastfed, P for trend < 0.001). Other initial feeding methods were significantly related to an increased risk of functional constipation as compared with breastfeeding exclusively at 1 month of age (partial breastfeeding: adjusted OR [95% CI] 1.17 [1.11, 1.23], formula feeding only: 1.23 [1.07, 1.40]) and 6 months of age (partial breastfeeding: adjusted OR [95% CI] 1.18 [1.12, 1.24], formula feeding only: adjusted OR [95% CI] 1.42 [1.20, 1.68]). CONCLUSION: This large nationwide survey revealed a possible protective effect of a prolonged breastfeeding period duration and early exclusive breastfeeding in infancy on functional constipation at 3 years. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13006-023-00592-y.