Hepatitis B and the Case of the Missing Women

Abstract

In many Asian countries the ratio of male to female population is higher than in the West - as high as 1.07 in China and India, and even higher in Pakistan. A number of authors (most notably Sen, 1992) have suggested that this imbalance reflects excess female mortality and, as a result, have argued that as many as 100 million women are "missing." This paper proposes an explanation for some of the observed over-representation of males: the hepatitis B virus. I present new evidence, consistent with an existing scientific literature, that carriers of the hepatitis B virus have offspring sex ratios around 1.50 boys for each girl. This evidence includes both cross-country analyses and a natural experiment based on recent vaccination campaigns. Hepatitis B is common in many Asian countries, especially China, where some 10 to 15% of the population is infected. Using data on viral prevalence by country as well as estimates of the effect of hepatitis on sex ratio, I argue that hepatitis B can account for about 45% of the "missing women": around 75% in China, between 20% and 50% in Egypt, and West Asia, and under 20% in India, Bangladesh, Pakistan and Nepal.