Objective: To analyze the secular changes in height and weight of Chinese school children in recent 20 years, in order to take effective preventive strategies and measures to improve their physical fitness and health.
Methods: Students aged 7-18 year-old participated in the 1985, 1995 and 2005 National Survey on Students Constitution and Health were used as subjects. The LMS method was applied to draw the 5th, 50th and 95th smoothed percentile curves of height and weight, and comparison was analyzed between different years.
Results: From 1985 to 1995, the 50th percentile of average height increased by 3.1, 3.5, 2.2 and 2.8 cm, and the 50th percentile of average weight increased by 3.2, 1.9, 2.0 and 1.3 kg, for urban boys, rural boys, urban girls, rural girls respectively. The average increments of height were 2.0, 2.3, 1.3 and 1.7 cm, and the average increments of weight were 3.1, 1.9, 1.7 and 1.2 kg during 1995 to 2005. The secular growth trends in the recent 20 years were: (1) height and weight had increased in each age group of students. (2) the 95th percentile curves of height and weight were higher than 50th and 5th percentile curves. (3) the average increments per decade in rural students were higher than those in urban students. (4) the average increments of height per decade for aged 18 year-old were lower than those in other age groups. (5) the average increments of height during 1985-1995 were higher than that during 1995-2005, but increments of adult height during 1985-1995 were lower than that during 1995-2005.
Conclusion: A significant secular increase in height and weight was found in school children aged 7-18 year-old in China, and the secular increase was more obvious among well-grown school children.