Maternal intake of Natto, a Japan's traditional fermented soybean food, during pregnancy and the risk of eczema in Japanese babies.

BACKGROUND There are reports that the maternal diet during pregnancy may affect development of babies' eczema. We sought to investigate the association between the maternal diet during pregnancy and the risk of eczema in infancy in Japan. METHODS A birth cohort was set up at 2 hospitals in Chiba city. Dietary habits concerning fish, butter, margarine, yogurt and natto during pregnancy was obtained from mothers just after delivery. The intake frequencies of these foods were classified into four groups: 1) daily, 2) 2-3 times a week, 3) once a week and 4) once a month or less. Diagnosis of eczema at 6 months of age was made by the presence of an itchy rash that persisted more than two months. RESULTS Valid data on 650 mother-baby pairs were obtained. No relationship between frequencies of the maternal intake of fish, margarine and yogurt during pregnancy and the onset rate of the babies' eczema were observed. For butter consumption, the incidence of babies' eczema was significantly higher in the group with daily intake than in those with an intake 2-3 times a week or less (p = 0.044). For natto, incidence of babies' eczema was significantly lower in the group with everyday intake than those eating it 2-3 times a week or less (p = 0.020). CONCLUSIONS High frequency intake of natto during pregnancy possibly reduces the incidence of eczema in children at 6 months of age.