Hepatitis B and the Case of the Missing Women

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 Amartya Sen) have suggested that this imbalance reflects excess female mortality and have argued that as many as 100 million women are “missing.” This paper proposes an explanation for some of the observed overrepresentation of men: 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…