Something already gave. The fertility rate in the US and Europe are below the population replacement rate. The fertility rate in China is below the population replacement rate. About the only place it isn't is Africa, and give them office jobs and better access to birth control and it would be there too.

It's actually becoming a problem the other way, because the fertility rate is dropping too fast, and then you end up with a top-heavy population which has too many retirees and not enough working-age people to support them.