The 2009 Investigative Report on the Current State of Infertility in China, which was released at the China International Summit Forum on Infertility in August, found a significant decline in the average sperm count of men on the mainland, from about 100 million sperm per millilitre of semen 40 years ago to about 20 million to 40 million in recent years.

A survey of 18,000 people seeking treatment for infertility in Beijing found that 10 per cent had been trying to conceive for a year since getting married, 15 per cent had been trying for two years and 25 per cent for 10 years, the report said.

For women, the leading cause of infertility is the blockage of the fallopian tubes, mostly induced by abortions. In all, 66 per cent said their infertility had not been cured after repeated treatments.

The figure is alarming also because the problem is affecting the 25 to 30 age group seeking reproductive help.

Since the late 1970s, China has pursued a one-child policy, whereby couples are prevented from having a second child, except for rural couples when their first-born is female or members of ethnic minorities, and punished with heavy fines in case of violations.

Now medical experts conclude that abortion can cause complications for women who want to have children.

The best fertility clinics in China, like the Reproductive and Genetic Hospital of Citic-Xiangya in Changsha, see long queues of desperate couples, some coming from afar.

The situation is such that the hospital's president, Prof Lu Guangxiu, said it had implemented a waiting list system of up to a year to cope with demand. He said that the high number of abortions and increasing levels of obesity were the main reasons for rising infertility rates.

He also noted that pre-marital sex is widespread but information about contraceptive methods remains limited, so that many women resort to abortion to get rid of unwanted pregnancies.

Wang Tianping, vice-president of the Population Association of China, a non-governmental organisation set up by academics in 1981, warned that the problem of infertility has been underestimated. He warns that China might face labour shortages and a large pool of elderly who will have to be maintained by a generation of single children. Reproductive difficulties might make matters in unexpected ways.

Couples can still resort to in-vitro fertilisation, but the procedure can cost between 15,000 yuan and 25,000 yuan, a price that is well beyond the reach of many couples.