Gender difference in secular trends of body height in Chinese Han adolescents aged 18 years, 1985-2014

Abstract

Objective: To analyze the gender difference in secular trends of body height in Chinese Han adolescents aged 18 years from 1985 to 2014. Methods: Data were extracted from 1985, 1995, 2000, 2005, 2010 and 2014 Chinese National Surveys in Students' Constitution and Health. A total of 124 099 Chinese Han adolescents aged 18 years were included in the analysis. ANOVA test was used to compare the body height between different subgroups stratified by gender and the mean difference and ratio in body height were calculated. Quantile regression model was used to assess the association between body height and gender over time in the adolescents stratified by region or area. Results: The mean body height of adolescents aged 18 years increased significantly from 1985 to 2014 with the rate of 1.3 cm/decade in male adolescents and 0.8 cm/decade in female adolescents, and the highest increment occurred from 1995 to 2005 in both groups. Male adolescents were taller than female adolescents at each subgroup (P<0.05). Gender difference in body height increased from 11.1 cm in 1985 to 12.6 cm in 2014 and ratio remained to be 1.07-1.08. The body height was taller in adolescents in urban area than in rural area (P<0.05) and in northeastern China than in other regions (P<0.05) in both male and female adolescents. The body height of obese male adolescents had been taller since 2000 and the body height of obese female adolescents had been taller since 2010 than other groups. When adjusted for urban-rural areas, region, socioeconomic status and nutritional status, the body height increased over time at P5, P25, P50, P75 and P95 in both male and female adolescents, and the increments of gender difference in body height at different percentile ranged from 0.45 cm/decade to 0.57 cm/decade. When stratified by region, the gender difference in body height showed similar trend with total sample except P5 and P95 in northeastern China, the difference of increments were not significant. Conclusions: From 1985 to 2014, the gender difference in body height of Chinese Han adolescents aged 18 years increased, and male adolescents showed greater increase than female adolescents. Moreover, the adolescents in northeastern and eastern China had larger increment in body height. It is necessary to paid more attention to the adolescents in central and western China to promote their physical development.