I don't think the problem is necessarily the population numbers. I don't wanna be that person, but I am 100% that person, and I think balls to the wall capitalism is the real culprit here. governments and big corporations refuse to divest from unsustainable manufacturing resources and practices. if we were able to curb that (and I don't know how we'd be able to) then I think it'd result in measurable change much more effectively than expecting people to 1) have less sex or 2) have sex using effective birth control methods. you don't get the latter without REALLY good sex education and accessible healthcare and that doesn't sound like a package deal with the one-child policy

Let's be honest here- Yes resources can be scarce and populations have skyrocketed (but When has any established rule ever kept people from breaking the law?) BIGGEST consideration to your question is as Albert Einstein states "The definition of insanity is doing the same thing over and over again and expecting a different result". With this, you have to clearly look at previous outdated measures taken by countries (like China who did enact this law). Knowing how difficult it would be to enforce and control humans to breed, they took aggressive measures like having many woman forcefully sterilized after 1 child. (Imagine if her child dies) No life is ever guaranteed and this measure done to her is irreversible. Another valid example is of a woman (who was 9 months pregnant) had to have an abortion because her husband had a child from a previous marriage.(Life's precious instead of focusing on 1 option for salvaging earth's resources, humanity needs to push forward and find newer innovative options) Unsurprisingly, you can't guarantee gender diversity where in most countries the odds of many having a gender bias is skewed towards Male heirs (so in many of these cases there's a high probability of Femicide).Consequentially as years pass, these numbers show how some women must be kidnapped from regions and sold off into marriage/union because there are just not enough women to go around for the 1 child policy. Let's not mention that 1 child will be held accountable for the well being of his family 2 parents and 2 grandparents if they still live because of how the retirement system spans out. >https://www.youtube.com/watch?v=SE_ccFHjL_w Fact is people die every day but actually having a baby isn't that easy. Those 9 months aren't a guarantee of a long life either. Plus, we as humans aren't wired like machines where either men or woman can be programmed. Cases of infertility and abortions leave so much heartbreak. If your biggest concern is the planet. Then we must look into solutions that directly improve the quality of life all around. Invest in new technology bringing this world into better prosperous times>https://www.youtube.com/watch?v=2HubIBlnvko How about enforcing better eco-friendly laws where people shouldn't have such a detrimental foot print? Maybe working on creating work opportunities that pull back from activities that drain the limited resources or those that are counterproductive the the planets sustainability? IDK- Why not recycle wisely so earth can flourish like this man did>https://www.youtube.com/watch?v=El6AU3riRI8