[Atopic dermatitis in early infancy in Matuyama city: prevalence and seasonal variations].

From Jun 1996 to May 1999, 1280 infants were examined by the author 6 times from birth to 12 month-old in each 0, 1, 3, 6, 9, 12 month-old time at NTT Nishinihon Matuyama Hospital. The 12-month cumulative prevalence of AD was 28.5%. Out of the cases 82.2% showed the symptoms before 3 month-old. There were 217 male infants in AD group (59.5%). This percentage was significantly higher than 45.2% in non-AD group (p < 0.001). Approximately 70% cases in AD group had family history of allergic diseases. This ratio was significantly higher compared to 49.6% in non-AD group (p < 0.001). According to the season of birth, there were significant differences in the 12-month cumulative prevalence of AD (p < 0.005). Infants born in the spring, summer, autumn and winter showed 21.1%, 27.2%, 31.3%, and 33.9% of cumulative prevalence of AD respectively. The prevalence of AD at 3 month-old and the ratio that the symptoms appeared before 3 month-old also had similarly significant tendency (p < 0.001) (Infants born in the spring showed 15.4% and 73%. Infants born in the winter showed 31.5% and 92.9%). There were no relationship between the cumulative prevalence of AD and the precipitation.