During a Q&A at TED, philanthropist Bill Gates, co-founder of the Bill and Melinda Gates Foundation, was asked if his charity, by saving millions from dying of malaria and other diseases, is contributing to the problem of overpopulation in the world.

He was grateful to get the question, since it allowed him to clarify the very issue he started out with himself.

“This is a very important question to get right because it was absolutely key for me. When our Foundation first started up, it was focused on reproductive health. That was the main thing we did because I thought population growth in poor countries is the biggest problem they face. You’ve got to help mothers who want to limit family size have the tools and education to do that. That’s the only thing that really counts. Well then I came across articles that showed that the key thing you can do to reduce population growth is actually improve health. And that sounds paradoxical. You think, ‘OK, better health means more kids not less kids.’

“Well in fact, what parents are doing is they’re trying to have two kids survive to adulthood to take care of them. And so, the more disease burden that there is, the more kids they have to have to have that high probability. So there’s a perfect correlation that as you improve health, within a half generation the population growth rate goes down. In fact Hans Rosling, here at this conference, in two of my favorite speeches, actually showed that unbelievable correlation that population growth has gone down. Today, where is there high population growth? It’s in the places with the worst health conditions – northern Nigeria, northern India. And so the two problems go exactly hand in hand. If we improve health rapidly we will get the peak population to be as much as a billion below the current expected peak. That is about 8.3 billion versus 9.3.”

See the complete Q&A here.