Can Hepatitis B Mothers Account for the Number of Missing Women? Evidence from Three Million Newborns in Taiwan.

The ‘missing women’ phenomenon in many Asian countries has previously been regarded as the result of son preference and change in economic conditions. However, some studies later argued that since the sex ratio of the offspring of Hepatitis B mothers is around 150, half of the missing women can be explained by this natural disease. Using an atypical national data set from Taiwan, we demonstrate that the marginal probability of an HBsAg(+) mother having a male birth ranges only from 0.0010 to 0.0025. In addition, this estimate does not vary with birth order and the sex composition of previous children. Given that 15 percent of mothers are HBV carriers, the disease can only raise the sex ratio from a base line of 105 to 105.165 at most. Our estimates suggest that the effect of HBV mothers on the offspring sex ratio, and hence on the cause of missing women, is minimal. Finally, we find that a third or higher birth, particularly in families where the first two children are female, the probability that the third child is male rises by 0.02, from a baseline sex ratio of 105 to 115. * Ming-Jen Lin and Ming-Ching Luoh are, respectively, Associate Professor and Professor at the Department of Economics, National Taiwan University; the corresponding author is Ming-Jen Lin. Address for correspondence: Department of Economics, National Taiwan University, No.21 Hsu Chow Road, Taipei 100, Taiwan. Tel: 886-2-23519641ext 463, email: [email protected].