13 and a bride
Meet Mariama, 13, who has just discovered she is about to join the 40% of girls in Niger who marry before they are 15.
Early marriage can be catastrophic for girls. Many are pulled out of education and pregnancy can cause serious long-term problems - such as fistula, which leaves girls incontinent and in constant pain.
Plan is working with girls, their parents and communities to educate them about the consequences of child marriage, particularly the dangers to a girl's health if she gives birth before her body is ready.
Watch the full 14 minute video to see what happens to Mariama
1 in every 3 girls in the developing world is married by the age of 18.