b Calculated from body mass index and height for ages 4 through 8 years and older.
cents aged 9 through 13 and 14 through 18, and for young adults aged 19 through 30 were identified, and the weights for those heights were based on Body Mass Index (BMI) for the same individuals within the group. Since there is no evidence that weight should change with aging if activity is maintained, the reference weights for 19- through 30-year-old young adults are applied to all adult age groups.
The most recent nationally representative data available for Canadians (from the 1970–1972 Nutrition Canada Survey [Demirjian, 1980]) were reviewed. In general, median heights of children from 1 year of age in the United States were greater by 3 to 8 cm (1 to 2 1/2 inches) compared to children of the same age in Canada measured two decades earlier (Demirjian, 1980). This could be partly explained by approximations necessary to compare the two data sets, but more possibly by a continuation of the secular trend of increased heights for age noted in the Nutrition Canada survey when it compared data from that survey to an earlier (1953) national Canadian survey (Pett and Ogilvie, 1956).
Similarly, median weights beyond age 1 year derived from the recent survey in the United States (NHANES III, 1988–1994) were also greater than those obtained from the older Canadian survey (Demirjian, 1980). Differences were greatest during adolescence, ranging from 10 to 17 percent higher. The differences probably reflect the secular trend of earlier onset of puberty (Herman-Gid-