title: Health effects of family size: cross sectional survey in Chinese adolescents.
abstract: OBJECTIVE
  To determine whether only children differ in terms of morbidity, nutritional status, risk behaviours, and utilisation of health services from children with siblings, in China.
  
  
  METHODS
  A cross sectional survey was carried out using self completion questionnaires, anthropometry, and haemoglobin measurement in middle schools (predominant age 12-16 years) in three distinct socioeconomic areas of Zhejiang province, eastern China.
  
  
  RESULTS
  Data were obtained for 4197 participants. No significant differences were found between only children and those with siblings for some key indicators: underweight 19% v 18%, suicide ideation 14% v 14%, and ever smoking 17% v 15%. Only children were more likely to be overweight (4.8% v 1.5%), and to have attended a doctor (71% v 63%) or dentist (17% v 10%) in the past year. Sibling children are significantly more likely to be anaemic (42% v 32%) and to admit to depression (41% v 21%) or anxiety (45% v 37%). However, after adjusting for area, sex, and parental education levels only two differences remained: sibling children are more likely to be bullied (OR 1.5, 1.1-2.0; p = 0.006) and are less likely to confide in parents (OR 0.6, 0.3-0.8, p = 0.009). There were no significant differences in the key parameters between first and second born children.
  
  
  CONCLUSIONS
  We found no detrimental effects of being an only child using the indicators measured. Being an only child may confer some benefits, particularly in terms of socialisation.
authors.affiliation: Centre for International Child Health, Institute of Child Health, University College London, UK. hesketh@mail.hz.zj.cn
authors.forename: T
authors.initials: T
authors.lastname: Hesketh
authors.forename: J D
authors.initials: JD
authors.lastname: Qu
authors.forename: A
authors.initials: A
authors.lastname: Tomkins
mesh_terms: D000293:Adolescent; D002648:Child; D002681:China; D003430:Cross-Sectional Studies; D005191:Family Characteristics; D005260:Female; D006304:Health Status; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D009752:Nutritional Status; D016017:Odds Ratio; D009863:Only Child / Q000523:psychology*; D012959:Socioeconomic Factors