title: Temporal trends of main reproductive characteristics in ten urban and rural regions of China: the China Kadoorie biobank study of 300 000 women.
abstract: BACKGROUND
  Chinese women's reproductive patterns have changed significantly over the past several decades. However, relatively little is known about the pace and characteristics of these changes either overall or by region and socioeconomic status.
  
  
  METHODS
  We examined the cross-sectional data from the China Kadoorie Biobank cohort study that recruited 300 000 women born between 1930 and 1974 (mean age: 51 years) from 10 socially diverse urban and rural regions of China. Temporal trends in several self-reported reproductive characteristics, and effect modification of these trends by area and education (as a surrogate for socioeconomic status), were examined.
  
  
  RESULTS
  The overall mean age at menarche was 15.4 (standard deviation 1.9) years, but decreased steadily over the 45 birth cohorts from 16.1 to 14.3 years, except for an anomalous increase of ∼1 year for women exposed to the 1958-61 famine in early adolescence. Similarly large changes were seen for other characteristics: mean parity fell (urban: 4.9 to 1.1; rural: 5.9 to 1.4); mean age at first birth increased (urban: 19.0 to 25.9 years; rural: 18.3 to 23.8 years); and birth spacing increased after 1980 to over 5 years. Breastfeeding declined after 1950 in urban and, after 1980, in rural women; and 68% of urban and 48% of rural women experienced a terminated pregnancy. Mean age at menopause increased from 47.9 to 49.3 years.
  
  
  CONCLUSIONS
  There have been striking changes in reproductive factors over time and between areas among these Chinese women. Their effects on major chronic diseases should be investigated.
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China sarah.lewington@ctsu.ox.ac.uk.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lewington
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, ChinaClinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: LiMing
authors.initials: L
authors.lastname: Li
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Serini
authors.initials: S
authors.lastname: Murugasen
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Lai-san
authors.initials: LS
authors.lastname: Hong
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Bian
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Rory
authors.initials: R
authors.lastname: Collins
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Junshi
authors.initials: J
authors.lastname: Chen
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Hui
authors.initials: H
authors.lastname: He
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Wu
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Tianyou
authors.initials: T
authors.lastname: He
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ren
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Jinhuai
authors.initials: J
authors.lastname: Meng
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Richard
authors.initials: R
authors.lastname: Peto
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK, School of Public Health, Peking University Health Science Center, Beijing, China, Chinese Academy of Medical Sciences, Dong Cheng District, Beijing, China, Chinese National Center for Food Safety Risk Assessment, Beijing, China, Nangang Center for Disease Control, Haerbin, Heilongjiang, China, Jiangsu Centre for Disease Control, Nanjing, Jiangsu, China, Huixian Centre for Disease Control, Huixian, Hennan, China, Gansu Centre for Disease Control, Lanzhou, Gansu, China and Liuzhou Centre for Disease Control, Liuzhou, Guangxi, China.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000328:Adult; D001721:Birth Intervals / Q000706:statistics & numerical data*; D001942:Breast Feeding / Q000639:trends*; D002681:China; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D006801:Humans; D008423:Maternal Age; D008572:Menarche; D008593:Menopause; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies; D017584:Reproductive History; D012424:Rural Population / Q000639:trends; D014505:Urban Population / Q000639:trends
keywords: China; Reproductive; cohort study; temporal trends