If you look at the advanced countries, they are often the ones who exploited their resources and grew in size early. Britain, for instance, slashed their forests generations ago to get ahead. The US used to shoot herds of bison from trains. Now Britain and the US wag a finger at less developed countries for consuming the forests and ecosystems in their countries.
Similar with population growth and the concept of 'overpopulation'. If you assert we have overpopulation, you have to assert how you'll address it, and there's no way to do that without saying, "Some group of people doesn't get to have kids." That seems like a really bad thing to say.
I'm incredibly lefty, a self described socialist and eco-socialist, but I believe that we need to think differently than just "those people over there are destroying their environments and having too many babies!" We could start at home, transforming our own economy and society to live less exploitatively. We could reduce our own use of meat and dairy, for instance. We could ensure we had adequate housing for everyone, and medical care for everyone, both of which would lead to less waste. We could strictly limit single use plastics, remove older dams to improve fish stocks, set aside more land for forests, etc.