China's birth gender imbalance remains stubbornly large, despite public efforts to address the problem. In 2010, the sex ratio at birth was 1.19 boys for every girl -- the biological norm is around 1.05 -- meaning there were about 500,000 extra male births. The imbalance is blamed for a wide variety of social ills.
It's often assumed that the imbalance is driven by China's official One-Child Policy, which was introduced in the late 70s, combined with access to ultrasound and abortion. If a couple can only have one child -- or two in the case of rural families -- they tend to opt for a boy. Sex-selective abortion is illegal in China but difficult to enforce.
But an NBER working paper by economists Douglas Almond, Hongbin Li, and Shuang Zhang makes the case that the roots of the gender imbalance go back farther than the OCP. Specifically, they argue that it was the pro-market land reform policies and breakup of collective farms following the death of Mao Zedong that drove the trend in rural areas -- 86 percent of the country's population at the time. For rural couples, who were allowed to have two children and generally preferred at least one of them to be a boy, the second child was 5.5 percent more likely to be a boy after land reform was introduced in a given area. The introduction of the OCP, which happened around the same time, had an effect as well, but the authors find that it's almost entirely eliminated when you control for the effect of land reform.
Why exactly land reform had this effect is less clear. The authors consider a number of possibilities including gender bias in land distribution, increase in the demand for male labor, increase in demand for old age support, and the collapse of the rural medical system, but don't find empirical support for any of them. There is evidence to suggest that better educated, more affluent families are more likely to opt for the practice.
Whether or not land reform is actually the culprit, it shouldn't be too shocking that the OCP isn't -- or isn't exclusively -- to blame. Sex-selective abortion is common in parts of India, where no such laws exist. And as Mara Hvistendahl wrote for FP in 2011, "Once found only in East and South Asia, imbalanced sex ratios at birth have recently reached countries as varied as Vietnam, Albania, and Azerbaijan."
This doesn't mean that the policy isn't still a bad idea for other reasons, but scrapping it may not be the answer to bringing back China's missing women.