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. 2014 Aug;43(4):1252-62.
doi: 10.1093/ije/dyu035. Epub 2014 Mar 17.

Temporal trends of main reproductive characteristics in ten urban and rural regions of China: the China Kadoorie biobank study of 300 000 women

Sarah Lewington  1 , LiMing Li  2 , Serini Murugasen  3 , Lai-san Hong  3 , Ling Yang  3 , Yu Guo  3 , Zheng Bian  3 , Rory Collins  3 , Junshi Chen  3 , Hui He  3 , Ming Wu  3 , Tianyou He  3 , Xiaolan Ren  3 , Jinhuai Meng  3 , Richard Peto  3 , Zhengming Chen  3 ; China Kadoorie Biobank study collaboration
Collaborators, Affiliations

Temporal trends of main reproductive characteristics in ten urban and rural regions of China: the China Kadoorie biobank study of 300 000 women

Sarah Lewington et al. Int J Epidemiol. 2014 Aug.

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.

Keywords: China; Reproductive; cohort study; temporal trends.

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Figures

Figure 1.
Figure 1.
Time trends in mean age at menarche (a) by region and (b) by highest level of education
Figure 2.
Figure 2.
Time trends in reproductive characteristics, by region. (a) Parity, (b) mean age at first birth, (c) years between first and second birth and (d) mean duration of breastfeeding [All among women aged 35 years or over. (a) and (b): among women with at least one live birth; (c) among women with at least two live births; (d) among women who had ever breastfed]
Figure 3.
Figure 3.
Time trends in termination of pregnancy and miscarriage, by region. Percentage experiencing event = number of women with at least one such event/total number of women
Figure 4.
Figure 4.
Time trends in mean age at menopause (a) by region and (b) by highest level of education
See this image and copyright information in PMC

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