Over 42,000 couples in Beijing have applied to have a second child since the birth control policy was changed in February 2014, the city's family planning department said Tuesday.

As of the end of May, 42,075 couples in Beijing had submitted applications, 38,798 of which had been approved. Among those approved, 57 percent of the potential mothers were aged between 31 and 35 years old, according to Beijing's Commission of Health and Family Planning.

In February, the commission suggested that the new policy would increase Beijing's population by an expected 270,000, around 54,000 extra births each year until 2019 when the figure should begin to return to normal. By then, most couples who want a bigger family will already have a second child, the commission predicted.

About 1.45 million couples across the whole country, around 13 percent of those eligible, had applied for a second baby by the end of May.