The world's most populous nation is suffering lower fertility as up to 10 percent of the Chinese couples are unable to conceive, reproduction health experts have warned.

No large-scale infertility survey had been carried out in China and statistics were hard to come by, but reports contributed by regional research bodies indicated an average infertility rate between seven and 10 percent among married couples, said Prof. Wang Yifei, of the Shanghai Jiaotong University.

While delaying childbirth until after a woman turned 35 and multiple abortions were often to blame for infertility and miscarriages, Wang said male infertility was also on the rise in China, with sperm counts decreasing from an average 100 million per ml in the 1970s to 40 million per ml today.

"A certain percentage of the sperm donated by seemingly healthy college boys to our sperm bank in Shanghai are not eligible in terms of sperm count or motility," Wang said.

Though no official figure is available, experts believe more than 10 million Chinese families need artificial fertilization and many are undergoing fertility treatment.

A reproduction health specialist in Hangzhou, east China's Zhejiang Province, has attributed the rising infertility rates to stressful and unhealthy lifestyles linked to China's dramatic social and economic changes -- including obesity, drinking, smoking and environmental problems.

"The problem deserves attention from all walks of life because it threatens the quality and structure of our future population," said Prof. Huang Hefeng, of Zhejiang University, at an ongoing symposium on reproduction health in Hangzhou, capital of Zhejiang.

Almost 1,000 researchers and doctors attended the symposium to discuss a wide range of topics, including infertility, miscarriages and maternity and baby health.

About 22 million babies are expected to join China's 1.3 billion population this year, the year of the pig which is considered auspicious for births, up from an average 16 million a year from 2001 to 2006.

But demographers have repeatedly warned of a graying society in China.

According to the China Elderly Association, senior citizens will account for 11.8 percent of the population in 2020, up from the present seven percent. The elderly population will peak around 2030 and will last about 20 years. By the mid-21st Century, people aged over 60 are likely to exceed 400 million, and those over 65 will top 300 million.

(Xinhua News Agency April 9, 2007)