BEIJING, Dec. 18 (Xinhua) -- Nearly 40 percent of the families in Beijing in which both the husband and the wife are only children intend to have a second baby, ushering in the prospect of a sooner-than-expected baby boom for China's capital.

    Nearly 140,000 babies will be born in the city in 2010, sources with local population research organizations said on Monday.

    China's one-child family policy was enacted in the 1970s to curb a huge population explosion. In 2002 the law was amended to allow ethnic minorities to have more than one child and peasants to have a second child if their first was a girl. The Tibet Autonomous Region is not subject to the one-child policy.

    In recent years, big cities like Beijing and Shanghai have started to encourage families where both husband and wife are only children to have two children.

    Official demographic data show that there are more than two million only children in Beijing.

    The Beijing Research Institute of Population completed a two-month house-call-based survey in October of 1,315 couples who are only children and aged 20 to 34 in the Xuanwu, Dongcheng and Haidian districts of Beijing. According to the findings unveiled at the weekend, 35.9 percent of the surveyed said they were willing to have a second child, an increase of 19.5 percent over four years earlier.

    But more than 60 percent of the young couples said that not only were they not considering a second baby, they had ruled out childbearing for the time being.

    According to the Beijing-based Research Institute of Population and Labor Economy under the Chinese Academy of Social Sciences, there will be 40,000 women of childbearing age ready to have a second baby in Beijing in 2010. A baby boom is likely to occur in the city at that time, five years earlier than a previous estimate which did not take the second-child policy into account.