Impact of the great east Japan earthquake on the body mass index of preschool children: a nationwide nursery school survey

ObjectiveTo evaluate the impact of the 2011 great east Japan earthquake on body mass index (BMI) of preschool children.DesignRetrospective cohort study and ecological study.SettingAffected prefectures (Fukushima, Miyagi and Iwate) and unaffected prefectures in northeast Japan.ParticipantsThe cohort study assessed 2033 and 1707 boys and 1909 and 1658 girls in 3 affected prefectures and unaffected prefectures, respectively, all aged 3–4 years at the time of the earthquake. The ecological study examined random samples of schoolchildren from the affected prefectures.Primary and secondary outcome measuresThe cohort study compared postdisaster changes in BMIs and the prevalence of overweight and obese children. The ecological study evaluated postdisaster changes in the prevalence of overweight children.Results1 month after the earthquake, significantly increased BMIs were observed among girls (+0.087 kg/m2vs unaffected prefectures) in Fukushima and among boys and girls (+0.165 and +0.124 kg/m2, respectively vs unaffected prefectures) in Iwate. 19 months after the earthquake, significantly increased BMIs were detected among boys and girls (+0.137 and +0.200 kg/m2, respectively vs unaffected prefectures) in Fukushima, whereas significantly decreased BMIs were observed among boys and girls (−0.218 and −0.082 kg/m2, respectively vs unaffected prefectures) in Miyagi. 1 month after the earthquake, Fukushima, Miyagi and Iwate had a slightly increased prevalence of overweight boys, whereas Fukushima had a slightly decreased prevalence of overweight girls, compared with the unaffected prefectures. The ecological study detected increases in the prevalence of overweight boys and girls in Fukushima who were 6–11 and 6–10 years of age, respectively.ConclusionsThese results suggest that in the affected prefectures, preschool children gained weight immediately after the earthquake. The long-term impact of the earthquake on early childhood growth was more variable among the affected prefectures, possibly as a result of different speeds of recovery.