title: Low body weight and its association with bone health and pubertal maturation in Chinese girls.
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.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Three socioeconomic areas (rural, suburban and urban) in Beijing, China.
  
  
  METHODS
  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.
authors.affiliation: Department of Food Science and Technology, University of New South Wales, Australia. xdu@vetsci.usyd.edu.au
authors.forename: X
authors.initials: X
authors.lastname: Du
authors.forename: H
authors.initials: H
authors.lastname: Greenfield
authors.forename: D R
authors.initials: DR
authors.lastname: Fraser
authors.forename: K
authors.initials: K
authors.lastname: Ge
authors.forename: W
authors.initials: W
authors.lastname: Zheng
authors.forename: L
authors.initials: L
authors.lastname: Huang
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D001835:Body Weight; D015519:Bone Density; D002648:Child; D002681:China; D005260:Female; D006801:Humans; D016015:Logistic Models; D008572:Menarche; D009752:Nutritional Status; D011627:Puberty; D011884:Radius; D012016:Reference Values; D013851:Thinness; D014457:Ulna; D014944:World Health Organization