Secular trends in height among children during 2 decades: The Bogalusa Heart Study.

OBJECTIVE: To examine trends in height among 5- to 17-year-old children between 1973 and 1992. DESIGN: A panel design consisting of 7 cross-sectional surveys. PARTICIPANTS: All schoolchildren residing in Bogalusa, La, were eligible. A total of 24 070 examinations were performed. RESULTS: During the study period, the mean height of schoolchildren increased by 0.70 cm per decade independently of race, sex, and age. Trends were most pronounced among preadolescents, blacks, and boys, with 9- to 12-year-old black boys showing a height increase of 1.8 cm per decade. We observed a decrease in the number of relatively short children (<10th percentile of height) and an increase in the number of tall children (>90th percentile of height). Because a secular trend was not seen among the 15- to 17-year-old children, our findings likely reflect an acceleration of maturation. CONCLUSIONS: It has generally been assumed that secular increases in height among schoolchildren in the United States ceased by the mid-1900s. Our findings, which may be due to various environmental factors, demonstrate that care must be taken when using nonconcurrent reference data to assess the growth of children. Additional study is needed to determine if these secular trends are continuing and to examine possible explanations and consequences of these trends.