I just read the article from the Business Week by Robert J. Barro, a professor of economics at Harvard University, about the case of Asia’s Missing Women.

In Western countraies, such as the U.S., the ratio of male to female births is around 1.05. Higher male mortality leads to decreasing male-female sex ratios as the population segment gets older. In the big picture, the two forces cancel each other out, leading to an overall male-female ratio close to 1.

But Asian countries, as we have known, their culture is the big factor that makes the male-female ratios in Asian countries higher than the Western countries. For example, China has a one-child policy and men are regarded as someone who carries the family name. So, in the past, most of family chose to abandon their daughters or in the extreme case they killed the new born baby in order to have a son. However, with new technology like ultrasound, family will be able to decide if they want to have that child since they are still in the womb. This leads to the higher ratio between male and female.

However, new research by the Harvard economist Emily Oster, in her PhD thesis “Hepatitis B and the Case of the Missing Women,” suggests that biology explains the reason of missing women question.

There is plenty of evidence that parents infected by HBV are more likely to have male children. Places with substantial HBV- Asia, Alaska, and parts of the former Soviet Union- tend to have high male-female birth ratios. Studies in Greece and, vs France how to that HBV-positive parents had male-female ratios for children of 1.7 to 1. for those who are HBV-negative. This pattern is also true among immigrants, with those from high HBV areas, such as China, having high male-female offspring ratios in the U.S.

In Alaska, the use of the HBV vaccine in 1982 led to a sharp decline in high male-female birth ratios.

The missing women in Asian countries stems from not only the family behavior and government policy but also the biology that have big influence to the male-female ratio.

It is very interesting research.

Tae Athikomvittaya