[Secular trend in growth of Uygur primary and middle school students aged 7-18 years in Xinjiang from 1985 to 2019].

Objective: To understand the growth and development of Uygur primary and secondary school students aged 7-18 years in Xinjiang from 1985 to 2019, and to provide theoretical basis for formulating health promotion strategies.

Methods: In the study, 18 591 Xinjiang Uygur primary and secondary school students aged 7-18 years with complete body height, body mass and body mass index (BMI) data by the Chinese National Surveillance on Students' Constitution and Health in 1985, 2000, 2010 and 2019 were selected as the research objects. The growth rate of each age group in each adjacent two survey years and per decade were calculated, and a t-test on the mean of each index to analyze was used to analyze the difference between the years.

Results: During the period 1985-2019, except for the height of girls aged 17-18 years, the height and mass of Uyghur boys and girls in all the age groups increased significantly (P all < 0.01), and the growth range of height for boys and girls was 2.06-9.89 cm and -0.03 to 6.86 cm, respectively; the growth range of mass was 2.39-10.2 kg and 2.57-8.05 kg, respectively; the BMI for most age groups increased from 2000 to 2019, whose range was -0.94 to 0.86 kg/m² and 0.08-1.34 kg/m² for boys and girls, respectively. The growth range was greater for boys than for girls. Height and mass of boys and girls increased at the fastest rate in the first 15 years; the height of most age groups, mass and BMI of a few age groups decreased in the middle 10 years; overall turned to a positive growth trend in the last 9 years except for the mass of boys, and height of girls increased at the highest rate in all periods. Advancement of maximum increase/growth age (MIA) in height was greater than that in mass and BMI for girls; MIA in height did not change significantly in boys, but MIA in mass and BMI was significantly earlier.

Conclusion: The overall body shape indexes of Uyghur primary and secondary school students aged 7-18 years in Xinjiang during the 34 years showed an increasing trend with gender differences. The overall status of growth was in the early stage of a secular growth trend, requiring focused attention to the mass status of both sexes to prevent the emergence of abnormal nutritional status.