Philanthropist Melinda Gates is calling on religious and political leaders to embrace the role that birth control can play in helping lift families out of poverty.

"No country in the last 50 years has escaped poverty without making sure that women have access, voluntary access, to contraceptives," the co-chair of the Bill & Melinda Gates Foundation told CNBC's Becky Quick in an interview that aired Wednesday on "Squawk Box."

"What allowed women to go into the workforce in droves? It was the advent of The Pill. When women can choose to time and space the births of their babies, we know from great research ... that families are healthier, children are better educated, and families are wealthier," said Gates, who has a new book out, "The Moment of Lift: How Empowering Women Changes the World."

However, Gates said she has noticed that contraceptives are becoming less available in developing countries and in the United States. "I am incredibly frustrated and disappointed to see that systematically access to contraceptives being rolled back in this country. And the people that it has the most effect for are single moms living in not great circumstances, in low income neighborhoods." Gates, who grew up Catholic, blames religious and political leaders for the rollback.

Melinda Gates, who has two daughters and a son with husband, Bill, also reflected on her role as a mother and wife, and how the work-life balance evolved in her family.

"I don't think either of us when we entered the marriage really questioned, either one of us, what our roles would be. And clearly, he's running Microsoft and he has a huge job. But I think even what I expected of myself, we didn't stop and talk about it. So it wasn't until well into the marriage that I realized how much I was doing at home," she said.

At one point, she said, she turned to her husband, saying, "'Hey, I want to work, too. I enjoy working. And if I'm going to be able to do that, you need to take on more work.'"

Bill Gates then stepped up his role in the home, she said, telling a story about how he drove his daughter to kindergarten that was far from their house two days per week. She said his actions inspired other moms to get their husbands involved with the argument that "'if Bill Gates can do it, you can do it.'"

On New Year's Day 1994, Bill and Melinda were married after an office romance at Microsoft where Melinda worked from 1987 to 1996. About 25 years later, the couple is worth nearly $100 billion and rank No. 2 on the Forbes' list of the world's most wealthy people.

In the interview, she also said capitalism needs work, but it beats socialism and the U.S. is 'lucky' to have it