Nominated alongside Bénédicte Kurzen, Julien Goldstein and Oded Balilty, VII Photo member Stephanie Sinclair was unanimously selected as this year's winner of the Visa d'Or Features award for her work on child brides.

Sinclair is the first photographer to win three Visa d'Or prizes - she won the coveted award in 2004, 2010, and now 2012.

The project looks at how children continue to be forced into marriage in more than 50 countries around the world. In the past eight years, Sinclair has visited Afghanistan, Nepal, Ethiopia, India and Yemen, producing a strong body of work that has been praised as this year's best exhibition at Visa pour l'Image.

"I want to thank [Jean-François Leroy, the festival's director] for giving this issue so much attention," she said while accepting her award in a ceremony last week. "I'm really grateful and want to thank everyone who supported this over the years. There have been so many: National Geographic, Geo, VII, The New York Times Magazine, etc. I've been really lucky. Even though the industry is having a tough time, if you believe in something, if you know in your heart that it needs to be documented, you'll find people to publish it. You can do it."

Sinclair says she will continue to cover the issue of child marriage. "It's an issue in more than 50 countries around the world," she explained. "It's really hard for me – not as hard as for the girls, but it's definitely intense to work on this. I will continue and, in fact, I've just started a two-year campaign with the United Nations Population Fund and we'll keep on working on this with Jessica Dimmock [another VII Photo member]."

National Geographic has also published a list of NGOs that are encouraging families to delay marriage and give girls an opportunity to reach their full potential. To find out more, visit the National Geographic website.

For more on Stephanie Sinclair, visit www.stephaniesinclair.com.