# **1   Introduction**

In the wake of the One Child Policy of 1979, China’s fertility declined dramatically as intended. As fertility rates fell, however, the male fraction of births began to rise (Zeng et al. 1993). This is consistent with China’s history of intensified sex selection during periods when parents were faced with sharper choices about whether to invest in raising girls (Das Gupta & Li 1999). Sex selection also became easier with the spread of ultrasound technology from the 1980s,<sup>1</sup> enabling a shift from postnatal to prenatal sex selection (Goodkind 1996).<sup>2</sup> The continued rise in the sex ratio, however, has surprised and alarmed observers worldwide. The Chinese census in 2005 reflected a staggering sex ratio at birth of 119, implying that each year there are roughly 1 million more boys born than girls.<sup>3</sup> For cohorts born between 1985 and 2005, we estimate that there are 27 million more men than women,<sup>4</sup> implying a large number of men will fail to marry.

A “marriage squeeze” of this magnitude and duration can be expected to generate social change. Studies indicate several pathways of social change. A growing literature suggests that it increases women’s bargaining power. Where marriage market sex ratios are higher, women exercise greater bargaining power within the marriage (Porter 2009a, 2009b, Edlund et al. 2009). Households in regions with a greater bride shortage are also found to have higher savings rates if they have a son (but not if they have a daughter) than matched households in other regions (Wei & Zhang 2009). The authors conclude that as much as half of the increase in the household savings rate during 1990-2007 can be attributed to efforts to enhance households’ competitiveness in the marriage market. Consistent with this, Edlund et al. (2009) find that households in regions with higher sex ratios invest more in their sons’ educations. A study in Taiwan, China finds that with the sudden shortage of brides caused by the influx of the Nationalist army and government from the mainland in 1949, bride prices rose and women’s bargaining power within the household increased (Francis 2009).

Some have also suggested that high levels of enforced bachelorhood may raise levels of crime and violence. There are reports of abduction and forced marriage of some women in the Chinese media,<sup>5</sup> and also in some studies (Banister 2004). Edlund et al. (2009) have exploited time and geographic variation in the introduction of China's One Child Policy to estimate the impact of high sex ratios on crime rates; they find significant effects.

> 1 Anonymous sources reported 100,000 ultrasound machines in China in 1990 (Kristof 1993).

> 2 Postnatal selection continues to be an issue in China. Recent work by Das Gupta et al. (2009) finds that the child mortality differential between boys and girls has widened in recent years.

> 3 The calculation of SRB is somewhat disputed, with credible estimates ranging from 118 to 120. The figure for births in the prior year may be subject to biases – see Cai 2008 for a full discussion. However we find that the sex ratios are relatively consistent, with approximately the same ratio of males to females among 5-9 year olds in 2005 as among ages 0-4 in 2000. The figure we refer to here is the ratio of male to female children from birth to exact age 1.

> 4 Hesketh et al. (2008) report a higher figure of 32 million, but we believe this to be an overcount. Our estimate of 27 million takes better account of the available data and is more in line with previous estimates of 23.5 million by Poston and Glover (2005) for the twenty year period ending in 2000.

5 See for example the recent article in the China Daily reporting on a study by the Chinese Academy of Social Sciences, and relating the skewed sex ratio to abduction and trafficking of women and infants (http://bbs.chinadaily.com.cn/viewthread.php?gid=2&tid=657774).

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