China’s “Missing Girls”—Son Preference or Hepatitis B Infections?

A research brief from World Bank;

The imbalance of sex ratios among children and the associated human and social implications has received increasing attention from scholars, policymakers, and governments. Amartya Sen drew especially vivid attention to this by pointing out that over 100 million women were “missing.” [1].

Both India and China have vigorous public policies in place to encourage parents to view daughters as no less valuable than sons. The assumption underlying such policies is that a strong preference for sons is driving the imbalance in sex ratios.[2].

But in a recent paper, Emily Oster argues that up to 75 percent of the “missing girls” in China can be accounted for by the high prevalence of Hepatitis B infection.[3] If true, this would be especially good news for policy makers in China seeking to address the skewed sex ratios, because implementing a Hepatitis B vaccination campaign is far easier than reducing people’s preference for sons.

Unfortunately, Oster’s hypothesis that Hepatitis B accounts for most of the “missing women” in China is difficult to reconcile with demographic and medical data

Das Gupta found that data from a huge sample of births in China show that the only women with elevated probabilities of bearing a son are those who have already borne daughters (Figure 1).[4]

Those who have borne only sons show a mildly elevated probability of the next child being a girl—indicative of a mild preference for having a daughter if the sons are already safely in place.

A study of the sex ratio of aborted fetuses in China confirms that women who have only daughters account for the bulk of the excess of female fetuses among total abortions. These data are consistent with the view that son preference is the predominant explanation for the missing girls.[5]

A similar pattern of son preference is found across Asia, showing that parental discrimination against girls is related to the sex composition of their children.Studies in India, Bangladesh, and the Republic of Korea, based on data from before the availability of sex-selection technology (when households resorted to postnatal discrimination), show excess female child mortality concentrated among girls born into families which already have a girl.[6] …

In China, sex ratios have fluctuated sharply over the twentieth century, and these fluctuations seem to correspond to resource constraints and ideological shifts (Figure 3).

Sex ratios rose sharply when households were placed under severe resource constraints by the disruption of war in the first half of the century, and by fertility decline in the latter decades of the century, which reduced the number of times parents could “toss the coin” to obtain a son.

By contrast in Mao’s China, an ideology of gender equality backed up by collectivization and control over private lives sharply reduced the scope for households to prioritize resource allocation among its members. This is reflected in relatively normal sex ratios, with a muted rise even during the Great Leap famine.

It is highly implausible that the prevalence of Hepatitis B infection fluctuated in tandem with these political shifts. It appears governments have been correct to assume that son preference is the main factor behind the “missing girls” and to focus their policies on changing the cultural roots of son preference.

Related;
The Search for 100 Million Missing Women

Hepatitis B and the Case of the Missing Women
Response to Das Gupta (2005) Comment: "Explaining Asias Missing Women -- A New Look at the Data"

Cultural versus Biological Factors in Explaining Asia’s “Missing Women”:. Response to Oster

"Everyone is fundamentally alike"