Some fire-brand ecologists want to go back to "traditional" ways outside of the paths of modern intensive agriculture but fail to realize that traditional agriculture both have a higher ecological footprint and is much more labor intensive.
If you want to lower the impact of intensive agriculture, promote contraception and demographic decrease.
You don't need to promote demographic decrease (you might need to do something about the Catholic church, though ...). All you really need to do is improve the opportunities for women.
Once women have opportunities and don't need to worry about 4 of 5 children dying, suddenly they don't want to be pregnant so often.
Many of the most advanced countries are already under replacement level. I believe the US would be, as well, if it weren't for immigration.
No, couples who decide to have more children are not helping society. They are draining its resources. If you want kids, have only one and give her/him all the education and resources you can.
Re parents with many kids are draining resources - this holds true for countries like India, but certainly not regions like Europe. Here, farmers are paid by the EU for letting fields lie fallow, because there is only so much produce that is consumed in the EU. Also, consider the amount of food thrown away by supermarkets, which could be used if we were content with eating crooked looking cucumbers. An argument might be that those extra kids still deplete scarce resources by proxy, e.g. oil.. but as we are slowly transitioning to solar and wind power, this might almost entirely go away.
Meanwhile, while it looks as if most continents are going in the right direction, we need to stop the extremest religious/political warrior movments prevalent in North Africa, Middle East and South East Asia.
Eg. In Somalia, a lot of men want 20 kids, and while I can't personally understand why, it's encouraged by religious leaders. It's apparent that Somalia itself won't sustain that in only a generation. This can only lead to conflicts, presumably with richer regions. There are so many pear-shaped scenarios to go to from there, but I leave to your own imagination what a highly industrial neighbouring region could come up with if cornered.
Hint: that region have only minor concerns about locking down the borders, setting up incentives that leads to that whole ships filled with people and kids drowing. Ther might be some public lamenting but no policy changes.