Association of breastfeeding with caregiver-reported physician-diagnosed allergies in children: the Japan Environment and Children’s Study

Breastfeeding has been linked to children’s susceptibility to allergic diseases. However, few large epidemiological studies have correlated breastfeeding patterns with the prevalence of allergic diseases in infants. Following exclusions from a dataset comprising 104,043 records from the Japan Environment and Children’s Study, participants were divided into four groups based on the breastfeeding pattern in the first 6 months of life: exclusively formula-fed for 6 months (only formula), breastfeeding for < 6 months, breastfeeding for 6 months with formula (non-exclusive breastfeeding [non-EBF]), and exclusive breastfeeding for 6 months (EBF). The outcomes assessed were four physician-diagnosed allergic diseases reported by caregivers—bronchial asthma, allergic rhinoconjunctivitis, food allergy, and atopic dermatitis—until 6 years of age. Multivariable regression analyses were performed to calculate risk ratios for allergic diseases using the only formula group as reference. The EBF group exhibited reduced risks of bronchial asthma at 1 and 2 years of age and of allergic rhinoconjunctivitis at 2 years of age. In contrast, the non-EBF and EBF groups showed increased risks of food allergy at ages 1 and 2. Adverse associations of EBF with the 1-year prevalence of food allergy were observed up to the age of 3 years in male infants. Breastfeeding during the first 6 months of life shows both protective and adverse associations with the 1-year prevalence of allergic diseases up to the age of 3 years, which diminish thereafter. These associations are sex-dependent. UMIN000030786 (2018–01-15)