More than a quarter of China's 20 to 29-year-old women have had an abortion, a conference heard yesterday.

There are 100 million Chinese women in that age group and 27.3 percent of them have had surgery, a conference on women's health was told.

The high abortion rate was related to people's lack of knowledge about contraception and the improper selection of contraceptive measures, experts told the conference in Shanghai.

The nation conducted some 13 million abortion operations a year.

Of abortions carried out in Shanghai, about 62 percent of women were in their 20s.

Over 55 percent of women in China had more than one abortion. The Shanghai figure was 44.1 percent.

A survey of 8,846 women having abortions in Beijing's 10 hospitals found 35.97 percent of them had a second abortion within six months.

Dr Liu Xiaoai, vice director of the Shanghai Institute of Family Planning Technical Instruction, said oral contraceptive pills were an effective method of birth control.

More than 40 percent of European women between 15 and 45 used oral contraceptives, while the percentage was just 2.6 percent in China's mainland.

"It is because of Chinese women's poor awareness of oral contraceptives and misunderstanding on the side effects of long-term use of such pills," Liu said.

Many women on the mainland take morning-after pills instead but these have strong side effects and should be limited to within three times per year, she added.