Philippine President Benigno Aquino III Monday endorsed a reproductive-health bill designed to reduce the country's high birthrate and introduce mandatory sex education in schools, despite strong opposition from the Roman Catholic Church.

Aquino's bold move to take on the Catholic Church - which played a significant role in putting his late mother and democracy icon Corazon Aquino in power in 1986 - was met with threats from the Christian leaders who vowed to campaign against the lawmakers favoring the bill in next year's election.

Aquino addressed a multi-party group of at least 180 lawmakers at the presidential palace, eliciting a general agreement to discuss the bill's contents.

The bill, under consideration by the Philippines House of Representatives, requires the Department of Health to distribute "medically safe, legal, accessible, affordable and effective reproductive health care services nationwide," and mandates "age-appropriate reproductive health and sexuality education" from the fifth grade through high school.

"God have mercy on him and on us," said Fr. Melvin Castro, executive director of the Catholic Bishops' Conference of the Philippines-Episcopal Commission Monday, referring to the President, two days after the Church led a rally to protest the bill. He warned that the Church would not take the move lightly, saying "2013 is just around the corner," reported the Philippine media.

Even if the Philippines House approves the bill, its backers will need to gain support from the Philippines Senate for its execution - a task that analysts say could be difficult, according to reports.

According to a United Nations Population Fund (UNFPA) report, the "unmet need" for family planning in the country, or the percentage of women who do not want to become pregnant but are not using contraception, grew from 15.7 percent in 2006 to 19.3 percent in 2011. The "unmet need" is the highest among poor women (25.8 percent), adolescent girls (37 percent), illiterate women (29.2 percent) and women in ARMM or the Autonomous Region in Muslim Mindanao (35.8 percent).

A U.N. report titled 'Fertility Decline in the Philippines' explains the reason behind the high birthrate in Philippines: "A large majority of the Filipino population professes allegiance to the Roman Catholic faith. There is also a sizeable Muslim minority in the southern Philippines. A common explanation for the slow pace of fertility decline in the Philippines as compared to other Asian countries is the alleged pronatalism of these two religions."

"Our view is that religion does not exercise a strong direct influence on fertility desires, but that it is a major factor influencing population policy and programs. Church opposition to contraception has been a major factor in preventing the government - both national and local - from committing funds for population programs," the report says.

"In Philippine society there is a norm against having but one child, because most parents believe that it is not healthy to grow up alone without siblings," the report says, exploring the social conditions that lead to population growth.

"Newlyweds or couples who are without children are often objects of curiosity and jokes - it is assumed that something must be wrong with the relationship if marriage does not result in childbearing. There is no preference for sons or daughters, rather a strong preference for having both a son and a daughter, an outcome many couples will not achieve if they have just two children."

The Philippines has one of the highest birthrates among Asian nations with some 25 births per 1,000 people every year, which could double the population within three decades. While in the U.S., the rate is 13.7.

Economists suggest that the country needs to take necessary steps to bring down the population growth to tackle problems such as poverty and weak infrastructure.