Association of Feeding Practice with Childhood Overweight and/or Obesity in Affected Areas Before and After the Great East Japan Earthquake.

The effect of breastfeeding on weight status of individuals after a large-scale natural disaster in a developed country is unclear. We aimed to investigate the association of breastfeeding with childhood overweight and/or obesity in areas affected by the Great East Japan Earthquake. From health examination records of 15,563 children, we retrospectively obtained anthropometric and feeding practice (formula, mixed, and breastfeeding) data during early childhood. According to their age at the time of the earthquake, we subdivided the children into study groups 1 (42-48 months), 2 (18-24 months), and 3 (<3 months). Overweight, obesity, and underweight were defined on the basis of body mass index. To assess the association between feeding practice at 3 months of age and the risk of overweight and/or obesity at 3 years of age, we developed generalized linear mixed models that included a random effect of the municipality of residence; for this analysis, we combined "mixed feeding" and "formula feeding" into a single category: "mixed plus formula feeding." Mixed- plus formula-fed children had a significantly higher risk of overweight and/or obesity than breastfed children in all three study groups (odds ratios, 1.20-2.22; all  ≤ 0.047). The rate of underweight at 3 years of age was ≤0.3%, irrespective of feeding practices. Breastfeeding, even during a large-scale natural disaster in a developed country, maintained its protective effect against overweight and/or obesity in childhood.