MANILA, Philippines — The Philippines’ annual population growth rate has slowed as more people in the predominantly Catholic country use contraception.

Results of the 2015 census show the population grew 1.72 percent last year, down from 1.9 percent during the previous census in 2010, the Commission on Population said.

The population of 100.98 million was half a million lower than what was forecast in 2010, the commission’s Executive Director Juan Antonio Perez III said.

The Philippines is the 12th most populous country in the world, according to United Nations data.

Its population will reach 103.48 million by the end this year, under calculations using the same growth formula, Perez said.

Perez said the use of modern contraceptives has increased, with 45 percent of couples using modern contraceptives as of last year, up from 38 percent recorded by a national survey in 2013.

“We have noted an increase in the use of modern contraceptives between 2013 onwards,” he said in a telephone interview, adding that fact and a natural decrease in fertility because women are choosing to have less children could also be a factor behind the slower population growth rate.

A national law that provides government funding for contraceptives was passed in 2012 despite strong opposition from Catholic leaders. The law took effect after the Supreme Court ruled in 2014 that it was constitutional except for a few provisions.

Perez said the census results, which were officially unveiled last week, also showed family size differed among socio-economic classes. Richer Filipinos have one or two children while the poorest have five or more children, or two children more than what women say they want, he added.

“We also noted in the census that it is the poorer regions of the country out of Manila which have higher fertility and we presume large numbers of the poor are in those regions,” Perez said.

With the slower population growth rate, he said the Philippines’ population is expected to double in 40 years, or two years longer than had been expected, giving the country more time to prepare and to exert more efforts to reduce the unmet need for family planning of some 4 million to 5 million couples who want to limit or space their children.

But he said a suggestion by the Philippines’ likely next president, Rodrigo Duterte, for families to limit their children to three cannot be mandated. Perez said under the law, families are given informed choice to decide on the number of children they could have.