Leyla Gouzaye knew the trauma her 14-year-old niece would face when the girl was promised in marriage to an older man in their Niger village.
Ms. Gouzaye herself had been married at 14 to a 34-year-old man she didn't know, in order to pay an uncle's debt.
After falling pregnant and running away, she has joined the ranks of young activists across West Africa who intervene to stop child marriages in their communities, often risking family estrangement to save other girls from a similar fate.
Niger has the world's highest prevalence of child marriage, according to the UN children's agency (UNICEF), with three in four girls married under the age of 18.
Driven by poverty, religion, and insecurity, marrying off girls once they reach puberty or even before is a deeply engrained tradition in much of West and Central Africa, but with detrimental effects on health, education, and development.
As leaders from across the region met at a landmark conference in Senegal this week to confront the issue, Gouzaye and other youth activists also came together to share strategies and ideas.
Now 21, the student said she managed to stop her niece's marriage and those of several friends.
"I explained the problems I had experienced, and I gave the parents' numbers to the police," she told the Thomson Reuters Foundation. The authorities threatened legal action if they did not call off the marriages, she said.
"Now we're all in our final year of high school together."
The legal age of marriage for girls in Niger is 15, with a law proposed but not yet passed to change it to 18.
Girls rarely go to the police but are increasingly aware that they can contact organizations who will send a representative to talk to their parents, Gouzaye said.
More and more girls are seeking support, said Niger country director Johnson Bien-Aime of child rights organization Plan International, which has stopped several marriages in this way.
"It's starting to change," Gouzaye said. "There are lots of girls who have escaped because they know their rights."
'Give me in marriage'
Sometimes the challenge is convincing girls themselves not to marry, said Hadja Idrissa Bah, an 18-year-old from Guinea.
"Girls are in a hurry to get married, but they don't understand the consequences. They don't understand what they will suffer," she told the Thomson Reuters Foundation.
Having an unmarried teenager in the family is seen as a risk in parts of Africa, because if she flirts with boys, draws attention, or has sex it would bring shame on the family.
"Parents say because I am a girl, I can't go out with friends, I can't mess around, etc," said Ms. Bah. "So some girls say, 'I can't take it anymore. Give me in marriage because I want my freedom.'"
Bah created an association called the Young Girl Leaders' Club of Guinea, which holds debates and has campaigns to teach girls what marriage entails.
People also contact the club to intervene in cases of child marriage, said Bah. She has a police contact whom she calls.
"We make a plan of how to approach the parents delicately, and if they don't come around, they apply the law," she said.
The legal age of marriage in Guinea is 18, but one in two girls is married before that.
Experts say laws against child marriage are rarely enforced, but strategies such as working with religious leaders, improving girls' access to education, and promoting sexual and maternal health have helped bring down rates.
Girls' empowerment is also part of the solution, said Aminata Gba Kamara, a 19-year-old from Sierra Leone.
"Girls in our country need so many things," she said. "They need psychosocial support, they need counseling. Their esteem is very low."
Many girls think they need husbands for protection, while others are unable to imagine a life outside the home, she said.
Kamara organizes career talks with successful women in schools, encourages girls to do extracurricular activities and helps them figure out how to make use of their talents.
"I am not a victim of child marriage, but I feel the pain of what these girls go through," she said.
In several cases, she has rallied teachers and counselors to help particularly vulnerable girls stay in school.
Ten years ago no one wanted to talk about child marriage, but now momentum is building to end it, said Francoise Moudouthe, head of Africa engagement at advocacy group Girls Not Brides.
Although world leaders have pledged to stamp out child marriage by 2030 under the U.N. Sustainable Development Goals, at current rates it will take over 100 years to end it in West and Central Africa, according to UNICEF.
Still, some young people are optimistic.
At the youth summit in Senegal, girls and boys shared recommendations: use local radio for awareness campaigns, get teenagers to spread the message on social media, create a mechanism for the African Union to track countries' progress.
"I think our generation has understood," said Bah. "Our place is not in the home, but at school."
This story was reported by the Thomson Reuters Foundation.