by Wei Xing Zhu, professor; Li Lu, professor and head of department; Therese Hesketh, senior lecturer
China’s excess males, sex selective abortion, and one child policy: analysis of data from 2005 national intercensus survey
Abstract
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.
Discussion
The findings paint a discouraging picture of very high and increasing sex ratios in the reproductive age group in China for the next two decades. The sex ratio increased steadily from 108 (108 to 109) in the cohort born between 1985 and 1989 to 124 (123 to 124) in the 2000 to 2004 cohort. However, the ratio then declined to 119 (119 to 120) for the 2005 cohort, perhaps indicating the beginning of a reduction in sex ratios for the future. Sex ratios were outside the normal range for almost all age groups in almost all provinces. The sex ratios rose dramatically between first and second order births, with very high sex ratios for the very few higher order births. Tibet and Xinjiang were the notable exceptions. The highest ratios were seen in the centre and south of the country, in the highly populous provinces of Henan, Jiangxi, Anhui, Guangdong, and Hainan. Extrapolating from this 1% sample to the whole country, we estimate that an excess of 1 132 000 boys were born in the 12 months to October 2005 and that an excess of 32 706 400 males under the age of 20 existed in the whole of China at that time, 18 497 000 of them under the age of 10.
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