1. ¹Department of Food Science and Technology, University of New South Wales, Australia
2. ²Department of Animal Science, University of Sydney, Australia
3. ³Chinese Academy of Preventive Medicine, China
4. ⁴Beijing Fu Xing Hospital, China
5. ⁵Beijing Municipal Centre for Health and Epidemic Control, China
6. ⁶Beijing China-Japan Friendship Hospital, China

Correspondence: Dr Xueqina Du, Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia. E-mail: xdu@vetsci.usyd.edu.au

Guarantors: X Du, H Greenfield and DR Fraser.

Contributors: The study was designed by XD, HG and DRF; data collection was carried out by XD, WZ, LH and ZL. The study was supervised by HG, DRF and KG. XD did data analysis and prepared versions of the paper. HG and DRF finalized the paper. All authors read and commented on the paper.

Accepted 19 July 2002.

Abstract

Objective: To investigate the prevalence of low body weight in Beijing pubertal girls and to establish the cut-off for body mass index (BMI) for underweight for Chinese pubertal girls.

Design: Cross-sectional study.

Setting: Three socioeconomic areas (rural, suburban and urban) in Beijing, China.

Subjects: Random sample of 1214 adolescent girls aged 12–14 y from 13 middle schools.

Results: Using a modified Chinese reference, the rate of low body weight (BMI<18) was 32.2% (95% CI 29.6–34.8%). Compared with desirable weight girls (BMI=18–21), girls with low body weight had a lower bone age, delayed breast and pubic hair development, a lower rate of menarche, lower distal one-third radius and ulna bone mineral content (BMC), bone mineral density and bone width. Logistic regression showed that BMI was one of the predictors of one-third ulna BMC after adjustment for confounding variables. When comparing BMI<18 vs BMI=18–21, the risk of BMC being less than the median increased by 82% (odds ratio 1.82, 95% CI 1.06–3.13). Thinness and stunting rates assessed by WHO recommended cut-offs are also reported.

Conclusions: High prevalence of low body weight (BMI<18) was found to be a major health problem among Beijing pubertal girls. BMI<18 is confirmed as the cut-off for delayed general growth and development for Chinese girls and for screening girls at risk of lower bone mineral status.

Sponsorship: The research was supported in part by the Dairy Research and Development Corporation, Australia.