By the end of September, 53,034 couples in Beijing had submitted applications for a second child, out of which 48,392 couples were granted permission.
Of the potential second-time mothers, 57 per cent were aged between 31 and 35 years of age.
China introduced its family planning policy in the late 1970s to rein in population growth by limiting most urban couples to one child and most rural couples to two, allowing the birth of a second child only if the first child was a girl, state-run Xinhua news agency reported.
Beijing, with a population in excess of 20 million, estimated that the new policy would increase this number by more than 270,000, with around 54,200 additional births annually until 2019, when the figure will peak and begin to go down steadily.
China is world's most populous country with a population of over 1.3 billion people.