STORIES about Chinese men finding it difficult to find wives in future years have been prominent in the media over recent weeks. This is because the proportion of boys among newborn babies has been steadily rising in some parts of the country and has now reached a frightening level.

The fifth national census showed the sex ratio at birth in 2000 was 116.86, which means that for every 100 girls who are born, there are 116.86 baby boys.

The normal sex ratio at birth should be around 103 to 107.

Statistics from the Shanghai Population and Family Planning Committee said the sex ratio at birth among the city's residents is about 107 which falls at the edge of the normal range. But the sex ratio at birth among the 3.8 million migrant population living in Shanghai for over six months stands at over 120.

"The figure is rather serious if the statistics have been reached in a correct way," said Zhang Henian, deputy president of the Institute of Population & Development Studies at the Shanghai Academy of Social Sciences.

Birth rate up

In 2003, Shanghai saw about 83,000 new born babies. Among these, 26,000 babies were born to parents in the migrant population. The trend of recent years shows the overall birth rate among migrant people has been rising continuously.

"There are a variety of reasons for the high sex ratio at birth," said Ren Yuan, associate professor at the Population Institute of Fudan University. "Firstly, some people may conceal the birth of girls in order to get another chance to have a son."

If this is so, the number of girls being born may appear to be smaller than the true figure. "But after five years or so, this group of invisible girls may re-appear when they begin entering school, which could relieve the high sex ratio," the expert said.

But he said the main reason for the gender imbalance was still parental choice in favour of boys during pregnancy. According to traditional ideas, having a son was the symbol of family continuity. In village families, boys are thought to be much better labourers than girls.

"According to regulations, it is forbidden for hospitals to reveal the sex of the baby in advance, even though ultrasound can detect this information after four or five months of pregnancy," said a doctor surnamed Zhou at the Changning District Central Hospital.

Anyone providing baby sex examinations without medical authorization can be punished according to the hospital regulation.

"Generally speaking, big hospitals in Shanghai take this regulation very seriously," said the doctor, who used to work in the maternity department. "But unavoidably, if you are a good friend of the doctor, you may discover the result in advance."

In addition, the ultrasound equipment is not especially expensive, making it affordable by hospitals or clinics in small towns or villages where administrative controls are much looser than in Shanghai.

At present, the city has a migrant population of slightly under five million, according to statistics released by the city's Public Security Bureau and the Shanghai Statistics Bureau last August. Over 64 per cent of these people have lived in Shanghai for more than a year.

"I am not sure if the gender ratio 120 to 100 is correct. To me, the exact sex ratio at birth remains in question," said Ren. "To arrive at such statistics among migrant people is a difficult thing, especially since migrant women may not go to hospitals to give birth."

"But I think the high sex ratio at birth among migrant people is a fact, I just wonder if it could be quite so big," he added.

Actually, in 1970s, the sex ratio at birth in China was normal. Upon entering the 1980s, the ratio began to slip out of the normal range. The sex ratio in 2000 was 8.5 per cent, higher than in 1990. Such a high sex ratio at birth started to include inland provinces instead of just the coastal region, as it had before.

Major concern

According to Xie Zhenming, an official with the China Population & Development Research Centre, since the country popularized ultrasound technology in 1985, more women have sought abortions after discovering they are pregnant with a girl.

With the development of medical technology, amniocentisis can also now reveal the gender of a baby correctly, although the cost of this test is rather high.

The high sex ratio at birth has become a major source of concern. Many news media have carried stories about China having 30 million excess bachelors within 20 years, bringing the institution of marriage under heavy pressure.

"If the statistics are correct, we could definitely see such a situation," Ren said. "It may have some affect on society, but we needn't worry about it too much."

According to this expert, society has the ability to adjust. The expert estimated that in the future "marriage market" such situations as elderly wives and younger husbands along with a higher divorce rate could help to compensate for the unbalanced sex ratio.

"In addition, some research shows that nature has an invisible ability to balance the sex ratio," he said.

For example, in some regions with extremely unbalanced sex ratios, more girls begin to be born.

"But this is just an observation and supposition, we still need more research and data to support it."