The Caucasian 1st world developed countries are generally losing numbers year on year due to ageing populations and low birth rates. Their populations are shrinking. This is due to higher education and careerism, where people are either not marrying, or if married, having less kids. Sperm counts are also dropping fast among 1st world men.
The opposite is happening in 2rd world countries, where their populations are exploding as they industrialize and get better access to healthcare and basic amenities.
The 1st world need young workers to sustain their infrastructure and service industries, so are forced to open their borders to migrant workers to take up jobs in their service and infrastructure sectors.
Many 1st world countries, without a sense of self preservation, have made a huge mistake by allowing people who do not share their cultural norms, language, religions etc to flood into their countries to finally naturalize, and have effectively brought about their own cultural suicide.