What are the implications of the populations growth in developing countries and develop countries?

Developing countries mostly have subsistence farmers, so they need a lot of children to help with the farm work, which makes the population high. Meanwhile, developed countries are commercial farmers, so they don't need as much children, and most people that live n urban areas, can't afford to spend money on a lot of kids, so they stick with 1 or 2 kids, which does not make the population as drastically high.