A counterpoint thread to the part about sperm count: https://twitter.com/lymanstoneky/status/1372178337016201224

Some points are that it's going back up again and is largely caused by poor sleep health. Beyond that, I haven't looked this up but what is the actual relationship between lower sperm count and fewer children? I mean, you have maybe 2-3 children and millions of sperm, surely they are not linearly related.

Effects on mothers could matter a lot more, but also maybe they just don't want to do it.