The Bill and Melinda Gates Foundation has donated more than $1 billion for family planning efforts worldwide. This investment is due to Melinda Gates' commitment to the issue. Since 2012, she has made it her mission to help women in dozens of developing countries gain access to contraception.

She helps to lead an international campaign, Family Planning 2020, which is working to get birth control to 120 million more women by 2020. The campaign is "a global partnership that supports the rights of women and girls to decide, freely, and for themselves, whether, when and how many children they want to have."

Gates told the New York Times last year why the campaign is so important: "Access to contraception can unlock the cycle of poverty for women."

When girls and young women have access to contraception, they don't get pregnant so early in their lives. This lets them continue their education, which leads to more economic independence and better opportunities throughout their lives.

The campaign's progress report shows that preventing unwanted pregnancies has prevented millions of unsafe abortions around the world since 2012.

Access to contraception "is the beginning thing that unlocks a woman's potential," Gates says.