Western people aren't even replacing themselves without immigration Europe would be in a population decline.
The US still has a positive natural population growth but many countries do not.
I find the arguments for not having children a disastrous one.
Reproduction is effectively our prime directive as a life form. Furthermore it's utterly ironic that the people that could care for their offsprings the most seem to have the least interest in reproduction.
And arguably the best way to avoid and ecological disaster is to reproduce and teach the next generation better, with each child we also increase the chance of someone being born that will have a huge impact on society, technology and culture.