Many Chinese couples are restricted to just one child
Authorities in China have highlighted inadequate knowledge of contraception and poor sex education as major factors in the high number of abortions there.
There are 13 million abortions each year, compared to 20 million births, according to newly published research.
Researchers believe the real figure could be even higher because there are many abortions at unregistered clinics.
Other countries have higher rates. They include Russia - which some years has more terminations than births.
'More sex education'
The abortion figures were published in the China Daily newspaper.
Other Chinese media outlets have published similar figures, although it was not immediately clear when the research was carried out.
China imposed strict family planning rules in the 1970s in an attempt to limit the growth of its population.
Many pregnant women who have had their full quota of children have abortions to prevent unwanted births.
But young single women are most likely to have abortions in a country where there are 20 million births each year, the research found.
In its front-page story, China Daily said the high number of abortions was "cause for concern", adding that many women who have abortions are single and aged between 20 and 29.
"Sex education needs to be strengthened, with universities and our society giving more guidance," Li Ying, a professor at Peking University, told the newspaper.
An official from China's National Population and Family Planning Commission told the newspaper that most sex education was directed at married couples.
Another official at the commission said the figure of 13 million was based on its own research and on information gathered from hospitals over the last few years.
Although the number is high, China's abortion rate of 24 per 1,000 woman of childbearing age, as the rate is usually calculated, is far from the top of the international list.
According to UN figures, Russia is highest with more than 50. The US has 15 and Spain just under 12.
China began restricting the number of children each couple can have in 1978. Officials say this has prevented 400 million extra births.
In many cases women are restricted to just one child, although in rural areas some couples can have two children if the first is a girl.
These rules mean abortions are used in some places to ensure the population growth is kept low.
Some women even complain that they are pressured into terminating their pregnancies.