The philanthropist is spending $1 billion — and leveraging her ever-growing celebrity — to call more attention to the systemic problems facing women and girls. Now she's focusing even more on women's health.

French Gates says she is "immensely proud" of the work of the Bill and Melinda Gates Foundation, and the decision to step down as co-chair was not easy. Her last day is June 7.

Melinda French Gates, co-chair of the Bill & Melinda Gates Foundation, is funding efforts to elect more women to public office through her company, Pivotal Ventures.

"After a great deal of thought and a lot of work on our relationship, we have made the decision to end our marriage," the couple wrote in a joint statement.