title: Prevalence of grade 1, 2 and 3 thinness is associated with lower socio-economic status in children in Shanghai, China.
abstract: We aimed to investigate the prevalence of grade 1, 2 and 3 thinness among Chinese children and to explore their associations with socio-economic status (SES).
  
  
  
  A population, school-based cross-sectional study using multistage, stratified cluster random sampling. Grade 1, 2 and 3 thinness, overweight, obesity and severe obesity were defined by the International Obesity Task Force BMI cut-offs.
  
  
  
  Seven districts of Shanghai, China.
  
  
  
  Chinese children aged 3-12 years (n 84 075).
  
  
  
  In boys and girls, respectively, the prevalence of grade 1 thinness was 8·89 % and 11·78 %, of grade 2 thinness was 2·80 % and 3·74 %, and of grade 3 thinness was 2·23 % and 2·93 %. Compared with urban children, suburban children had higher prevalence of thinness. Children whose parent had low education had higher prevalence of grade 1, 2 and 3 thinness than those whose parent had high education. The prevalence of grade 2 and 3 thinness, obesity and severe obesity in low-SES children was higher than that in high-SES children, and the prevalence of grade 1 thinness was lower than that in high-SES children. Particular patterns of prevalence of grade 1, 2 and 3 thinness appeared in low-, middle- and high-SES children.
  
  
  
  The study describes associations of SES with grade 1, 2 and 3 thinness, overweight, obesity and severe obesity in Shanghai children. The patterns of thinness and obesity in Shanghai provide further insights into BMI patterns in mega-cities in developing countries.
authors.affiliation: 1Department of Clinical Epidemiology,Pediatric Translational Medicine Institute,Shanghai Children's Medical Center,School of Public Health and School of Medicine,Shanghai Jiaotong University,1678 Dongfang Road,Shanghai 200127,People's Republic of China.
authors.forename: Chang
authors.initials: C
authors.lastname: Chen
authors.affiliation: 2Department of Developmental and Behavioral Pediatrics,Shanghai Children's Medical Center,School of Medicine,Shanghai Jiaotong University,Shanghai,People's Republic of China.
authors.forename: Zhijuan
authors.initials: Z
authors.lastname: Jin
authors.affiliation: 2Department of Developmental and Behavioral Pediatrics,Shanghai Children's Medical Center,School of Medicine,Shanghai Jiaotong University,Shanghai,People's Republic of China.
authors.forename: You
authors.initials: Y
authors.lastname: Yang
authors.affiliation: 2Department of Developmental and Behavioral Pediatrics,Shanghai Children's Medical Center,School of Medicine,Shanghai Jiaotong University,Shanghai,People's Republic of China.
authors.forename: Fan
authors.initials: F
authors.lastname: Jiang
authors.affiliation: 2Department of Developmental and Behavioral Pediatrics,Shanghai Children's Medical Center,School of Medicine,Shanghai Jiaotong University,Shanghai,People's Republic of China.
authors.forename: Xingming
authors.initials: X
authors.lastname: Jin
authors.affiliation: 3Shanghai Key Laboratory of Children's Environmental Health,Xinhua Hospital,School of Medicine,Shanghai Jiaotong University,1665 Kongjiang Road,Shanghai 200092,People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Huang
authors.affiliation: 1Department of Clinical Epidemiology,Pediatric Translational Medicine Institute,Shanghai Children's Medical Center,School of Public Health and School of Medicine,Shanghai Jiaotong University,1678 Dongfang Road,Shanghai 200127,People's Republic of China.
authors.forename: Shijian
authors.initials: S
authors.lastname: Liu
mesh_terms: D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight / Q000453:epidemiology; D063766:Pediatric Obesity / Q000453:epidemiology; D015995:Prevalence; D012923:Social Class; D013851:Thinness / Q000453:epidemiology*
keywords: Obesity; Overweight; Prevalence; Socio-economic status; Thinness