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China’s excess males, sex selective abortion, and one child policy: analysis of data from 2005 national intercensus survey

BMJ 2009; 338 doi: (Published 09 April 2009) Cite this as: BMJ 2009;338:b1211
  1. Wei Xing Zhu, professor1,
  2. Li Lu, professor and head of department2,
  3. Therese Hesketh, senior lecturer3
  1. 1College of Law, Political Science and Public Administration, Zhejiang Normal University, Jinhua, Zhejiang 310347, China
  2. 2Institute of Social and Family Medicine, Zhejiang University, Hangzhou 310016, China
  3. 3Centre for International Health and Development, University College London, London WC1N 1EH
  1. Correspondence to: T Hesketh t.hesketh{at}
  • Accepted 27 November 2008


Objectives To elucidate current trends and geographical patterns in the sex ratio at birth and in the population aged under 20 in China and to determine the roles played by sex selective abortion and the one child policy.

Design Analysis of household based cross sectional population survey done in November 2005.

Setting All of China’s 2861 counties.

Population 1% of the total population, selected to be broadly representative of the total.

Main outcome measure Sex ratio defined as males per 100 females.

Results 4 764 512 people under the age of 20 were included. Overall sex ratios were high across all age groups and residency types, but they were highest in the 1-4 years age group, peaking at 126 (95% confidence interval 125 to 126) in rural areas. Six provinces had sex ratios of over 130 in the 1-4 age group. The sex ratio at birth was close to normal for first order births but rose steeply for second order births, especially in rural areas, where it reached 146 (143 to 149). Nine provinces had ratios of over 160 for second order births. The highest sex ratios were seen in provinces that allow rural inhabitants a second child if the first is a girl. Sex selective abortion accounts for almost all the excess males. One particular variant of the one child policy, which allows a second child if the first is a girl, leads to the highest sex ratios.

Conclusions In 2005 males under the age of 20 exceeded females by more than 32 million in China, and more than 1.1 million excess births of boys occurred. China will see very high and steadily worsening sex ratios in the reproductive age group over the next two decades. Enforcing the existing ban on sex selective abortion could lead to normalisation of the ratios.


  • Contributors: All the authors participated in the analysis and in preparing the tables and saw and approved the final version of the paper. ZWX is the guarantor.

  • Funding: This study was funded through a China-UK excellence fellowship for TH from the Department of Innovation, Universities and Skills.

  • Competing interests: None declared.

  • Ethical approval: Not needed.

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