Stature and pubertal stage assessment in American boys: the 1988-1994 Third National Health and Nutrition Examination Survey.

PURPOSE

To describe current stature and pubertal development in North American boys, and to compare these measures with measures observed approximately 30 years ago.

METHODS

We analyzed data (i.e., height, weight, and Tanner Stage) from the Third National Health and Nutrition Examination Survey (NHANES III), conducted between 1988-1994, and compared it to the National Health Examination Survey, Cycles II and III (HES II/III), conducted from 1963-1965 and 1966-1970. The surveys included physical examination and questionnaire components, employed cross-sectional designs, and are nationally representative. We used logistic regression to calculate median age at onset of pubertal stages.

RESULTS

NHANES III included 2481 boys aged 8 to 18 years. HES II comprised 3010 boys aged 8-11 years and HES III comprised 3514 boys aged 12-17 years. The mean heights of the oldest boys in both surveys did not differ significantly; however, at younger ages, boys in the more recent survey were taller (average height difference among those aged 8-14 years was 2.0 cm). Boys in NHANES III were also heavier and had higher body mass index than those in HES II/III. The median estimated ages of onset of pubertal stages in NHANES III were 9.9, 12.2, 13.6, and 15.8 years for genital stages 2-5, respectively, and 11.9, 12.6, 13.6, and 15.7 years for pubic hair stages 2-5, respectively. For some stages, the median estimated age of onset of puberty was earlier among boys in NHANES III than among those in HES III.

CONCLUSIONS

Differences in mean height at young ages, but not at older ages, suggest that the rate of growth among boys in NHANES III was faster than that of boys in the earlier surveys. This finding, coupled with the finding of earlier ages of onset of some pubertal stages, suggests that boys of this generation may be maturing more rapidly than did boys in the past.