The one child family policy has been in force in China since 1979 and was intended as a short term measure. To examine the impact of this policy, researchers analysed data from the 2001 national family planning and reproductive health survey.
Data were obtained from 39,585 women aged 15-49. The total birth rate has dropped from 2.9 before the policy to 1.94 in women over 35 and 1.73 in women under 35.
Most women want small families: 35% would prefer one child, 57% preferred two, and only 5.8% more than two. The preferred number decreased with age and higher education, and was lower among women in urban areas.
The male to female ratio was 1.11 in 1980-9 but rose sharply to 1.23 in 1996-2001. The sex ratio for first births was higher in urban areas, where only one child is allowed, suggesting that some people select the sex of their child at first birth.
Over a third of women had no sex preferences. Of those who did, 72% preferred a girl and a boy, whereas 10% preferred girls (most of these were women under 25 who lived in urban areas).
It is not clear how much these demographic changes are due to the one child policy, they add. Many countries are seeing decreases in fertility rates, and neighbouring east Asian countries have some of the lowest total fertility rates in the world. Thus the fertility rate may have continued to fall even without the policy.
Likewise many other Asian countries that have declining birth rates and traditional preferences for male babies are seeing serious sex imbalances. Even without the policy, sex selective abortion would be likely to continue, although it would probably be less common.
This can only be solved by a change in attitudes towards female offspring. The finding that many younger women in urban areas now express a preference for girls provides evidence that attitudes may be changing.
These findings have clear implications for decisions about future population policy. A relaxation in the policy could be considered in the near future. It is unlikely that a baby boom would result, and such a change in policy might help to correct the abnormal sex ratio, they conclude.
An accompanying editorial discusses the impact of this policy on China's economy.