The head of the UN Population Fund says the agency's "new mantra" is to keep girls in school until age 18 "in every nook and cranny of the world" as a key means of slowing population growth.
The UN expects the world's population to reach 8.5 billion by 2030 and 9.7 billion by 2050.
Agency chief Babatunde Osotimehin says women tend to have fewer children if their first one is born after they've turned 18. He said previously that one in three girls is married before age 18.
Osotimehin told The Associated Press at a conference in Jordan on Friday that pushing for primary education is not enough.
He says that "we must up our game" as UN members prepare to ratify ambitious development goals for 2030 next month.
