According to this recent Bloomberg article, the world is expected to add more than 3 billion people by 2100. At the same time, the global average fertility rate is dropping. In 1960, it was five live births per woman. As of 2017, it had dropped to 2.43.
About half of all countries are now below the rate of replacement, which means they’re relying on immigration (places like Canada) and/or they’re relying on labor productivity gains to keep their economy growing (places like China).
The article is also fascinating in that it begins to consider the economic and cultural forces that shape the above fertility rates. Women in Saudi Arabia, for example, have one of the lowest labor force participation rates in the world. Only about 25% are in the workforce.
If you’d like to read the full article, you can do that here.