It's really one of my all-time favorite things to do. To go out and really see the kids and visit the moms who are in these programs because I think I really get to see what happens on the ground and connect with them about what changes are that happen in their lives because of some of the giving that we're able to do.

If I really believe all lives have equal value, and if I use contraceptives, which I do, and if I'm counselling my son and my two daughters to use them, how am I not serving the women who don't have access to the contraceptives they need?

Women are the centre of the family. It's the woman who decides what's eaten in the house, when to have the kids vaccinated; everything that has to do with the children's health revolves around her.

Despite the debunking, you have a small group in the last five years that hasn't wanted to vaccinate their children, for instance, for measles. Then, all of sudden, we got an outbreak of measles and kids were starting to die from measles.

We [with Bill Gates] started to make decisions about what we'd invest in. Then I actually started traveling for the foundation. I've probably been to India now eight times at least and Africa numerous times.

Around the world we have girls in primary school at about the same rate now as boys, but keeping them in quality secondary schools is where the world is lagging. I'm seeing a lot of countries look at this now.

Women speaking up for themselves and for those around them is the strongest force we have to change the world.