On Thursday, a law prohibiting child marriage went into effect in the Philippines, where one in every six girls marries before the age of 18.

According to the rights group Plan International, the country has the 12th highest number of child marriages in the world, with long-held cultural practices and gender inequalities impeding change.

However, the new law, signed by President Rodrigo Duterte and made public on Thursday, imposes prison sentences of up to 12 years for marrying or cohabiting with anyone under the age of 18.

People who arrange or solemnize underage unions face the same penalty.

"The state... views child marriage as a practice constituting child abuse because it debases, degrades, and demeans the intrinsic worth and dignity of children," the law states.

According to the government, the law is in accordance with international conventions on the rights of women and children.

Some parts of the legislation, however, have been suspended for a year to allow for a transition period for communities where child marriage is common.

According to a United Nations Children's Fund report released last year, more than half a billion girls and women worldwide were married as children. However, recent data show that the practice is declining globally on average.