Missing women, again

It is often said that women make up a majority of the world's population. They do not. This mistaken belief is based on generalizing from the contemporary situation in Europe and North America, where the ratio of women to men is typically around 1.05 or 1.06, or higher. In South Asia, West Asia, and China, the ratio of women to men can be as low as 0.94, or even lower, and it varies widely elsewhere in Asia, in Africa, and in Latin America. How can we understand and explain these differences, and react to them?

-- Amartya Sen, More than 100 million women were missing,

editorial article from The New York Review of Books, December 20, 1990.

This week's The Economist published a special report on the growing worldwide gender imbalance at birth, especially in some developing countries. For example, the article cited:

In China the sex ratio for the generation born between 1985 and 1989 was 108, already just outside the natural range. For the generation born in 2000-04, it was 124 (ie, 124 boys were born in those years for every 100 girls). According to CASS the ratio today is 123 boys per 100 girls.

As the consequence, within ten years one in five young men would be unable to find a bride because of the dearth of young women—a figure unprecedented in a country at peace.

What caused the highly skewed ratio? According to the article, it is the combination of 1) parents' strong preference over boys (for whatever reasons - economic or cultural), 2) declining fertility, either by policy or improved income, so nowadays parents tend to have a limited number of children, and 3) advanced in technology; cheaper ultrasound makes it possible to detect gender of fetus, hence parents might decide to abort the unborn if it was a girl ('Gendercide', as the article refers to it).

The article also linked this trend to socio-cultural changes, including problems. In a highly homogeneous Korea, inter-country marriage becomes more common and acceptable. In some parts of India, a bride can only marry a man from a different village if the groom's village provides another bride in exchange. In China, growing number of unmarried men has created pressure to crime and violence.

* * *

Skewed male-female ratio in developing countries has been an interest for long. The cited paragraph in the beginning was a summary of a series of papers Sen has written in the 1980s.

Where did the number come from? Let's take 1.05 as the 'normal' ratio of women to men.¹ It means that if a country like China has a ratio of 0.94, this alone amounted to more than 50 million deficit of women. Together with the female deficit in South Asia, Africa, and other developing countries, they added up to more than 100 million.²

The reason, as Sen argued, was 'discrimination' against girls in getting access to health care, medicine and nutrition. The term 'discrimination' here should be treated carefully. It may not be a clear case of discrimination, but different intra-household preference in allocating resources towards boys and girls, resulting in higher mortality rate of women compared to men.³

Some researchers have tried to come up with different explanations for the missing women. Emily Oster (2005) argued, Hepatitis-B could be one explanations. Unborn boys have more chance to survive if their mothers have Hep-B. High prevalence of Hep-B among pregnant mothers in those countries skews the gender ratio at birth towards boys. The missing girls were not missing, concluded Oster; they were never born at all. However, her later study in China with Gang Chen (2008) didn't show that Hep-B explains male-biased sex ratio. So the Hep-B hypothesis may still be doubtful.

That makes selective abortion, as reported in The Economist article, the likeliest. possible explanation, for now. Amartya Sen seems to agree. As he wrote in his 2003 article, revisiting his earlier one:

But another more important and radical change has occurred over the past decade.T here have been two opposite movements: female disadvantage in mortality has typically been reduced substantially, but this has been counterbalanced by a new female disadvantage—that in natality—through sex specific abortions aimed against the female fetus. The availability of modern techniques to determine the sex of the fetus has made such sex selective abortion possible and easy, and it is being widely used in many societies.

¹ Sen defined gender ratio as the number of women divided by men. Many (most?) other calculation define it as the other way round, multiplied by a hundred. So a ratio 0f 106 means for every 100 women there are 106 men. Doesn't matter which one we prefers as long as we know what it is.

² Using slightly different method, Klassen and Wink (2003) estimated a lower - but still large - number of 'missing' women, 89 million.

³See a paper by Monica DasGupta (1997) on how boys and girls received different allocations of health and nutrition, based on a survey data from India.