title: Parenthood and the risk of diabetes in men and women: a 7 year prospective study of 0.5 million individuals.
abstract: In women, higher parity has been associated with increased risk of diabetes later in life. It is unclear, however, whether this association is mainly due to biological effects of childbearing, or to socioeconomic and lifestyle factors associated with childrearing. We assessed the association between number of children and diabetes risk separately in women and men.
  
  
  
  Between 2004 and 2008, the nationwide China Kadoorie Biobank recruited 0.5 million individuals aged 30-79 (mean 51 years) from ten diverse regions across China. During 7 years of follow-up, 8,840 incident cases of diabetes were recorded among 463,347 participants without prior cardiovascular diseases or diabetes. Multivariable Cox regression yielded sex-specific HRs and 95% CIs for incident diabetes by number of children.
  
  
  
  Overall, ∼98% of all participants had children. In women, there was a J-shaped association between number of children and risk of diabetes. Compared with women with one child, the adjusted HRs for diabetes were 1.39 (95% CI 1.11, 1.73) for childless women, 1.12 (95% CI 1.07, 1.18) for those with two children, 1.23 (95% CI 1.16, 1.31) for those with three children, and 1.32 (95% CI 1.21, 1.44) for those with four or more children. In men, there was a similar association with risk of diabetes; the corresponding HRs were 1.28 (95% CI 1.02, 1.60), 1.19 (95% CI 1.12, 1.26), 1.32 (95% CI 1.21, 1.44) and 1.41 (95% CI 1.24, 1.60), respectively. In both sexes, the findings were broadly similar in different population subgroups.
  
  
  
  The similarity between women and men in the association between number of children and risk of diabetes suggests that parenthood is most likely to affect diabetes risk through factors associated with childrearing rather than via biological effects of childbearing.
authors.affiliation: The George Institute for Global Health, University of Oxford, 34 Broad Street, Oxford, OX1 3BD, UK.
authors.forename: Sanne A E
authors.initials: SA
authors.lastname: Peters
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.affiliation: Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, People's Republic of China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Bian
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
authors.forename: Iona Y
authors.initials: IY
authors.lastname: Millwood
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Bragg
authors.affiliation: Department of Prevention and Control of Non-Communicable Diseases, Heilongjiang Center for Disease Control and Prevention, Harbin, Heilongjiang, People's Republic of China.
authors.forename: Xue
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Gansu Center for Disease Control and Prevention, Lanzhou, Gansu, People's Republic of China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Ge
authors.affiliation: Department of Prevention and Control of Non-Communicable Diseases, Hunan Center for Disease Control and Prevention, Hunan, Changsha, People's Republic of China.
authors.forename: Biyun
authors.initials: B
authors.lastname: Chen
authors.affiliation: Huixian Center for Disease Control and Prevention, Huixian, Henan, People's Republic of China.
authors.forename: Yulian
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Prevention and Control of Non-Communicable Diseases, Meilan Center for Disease Control and Prevention, Haikou, Hainan, People's Republic of China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Li
authors.affiliation: China National Center for Food Safety Risk Assessment, Chaoyang District, Beijing, People's Republic of China.
authors.forename: Junshi
authors.initials: J
authors.lastname: Chen
authors.affiliation: Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, People's Republic of China.|Department of Public Health, Beijing University, Beijing, People's Republic of China.
authors.forename: Liming
authors.initials: L
authors.lastname: Li
authors.affiliation: The George Institute for Global Health, University of Oxford, 34 Broad Street, Oxford, OX1 3BD, UK. mark.woodward@georgeinstitute.ox.ac.uk.|The George Institute for Global Health, University of Sydney, Sydney, NSW, Australia. mark.woodward@georgeinstitute.ox.ac.uk.|Department of Epidemiology, Johns Hopkins University, Baltimore, MD, USA. mark.woodward@georgeinstitute.ox.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Woodward
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK. zhengming.chen@ctsu.ox.ac.uk.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D002681:China / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010290:Parents; D010298:Parity / Q000502:physiology; D011446:Prospective Studies; D012307:Risk Factors
keywords: Children; China; Diabetes; Men; Parenthood; Women