An ecologic study of the relationship between mean birth weight, temperature and calorie consumption level in Japan.

This study reports an ecologic analysis of the relationship between mean birth weight (MBW) and nutritional, medical, and social variables, using 1982 data for 47 prefectures in Japan. Correlation analysis showed that variables that correlated significantly with MBW were mean temperature (r = 0.63), total calorie intake (r = 0.56), and body mass index of women (r = 0.60). It is concluded that the MBW level in a given community represents the long and short term nutritional condition of mothers, and that the level may follow Bergman's law: 'In the same species, the body size of an animal increases along with latitude; that is, the lower the temperature, the larger the body size.'