I think it's because of an inchoate whole-species reaction to severe overcrowding: overpopulation.
I've noticed for years that every new law, every big cultural change is anti-natalist, against births. Women working, easy divorce, homosexuals, now trannies all made sterile or too screwed up to mate, easy birth control, easy and legal abortion ---- I could go on.
Well, one more: sex-selective abortions in many grossly overpopulated developed countries: China and India, for two. We haven't started that yet, but we will. The idea has forever been to abort (or expose, in the old days, after birth) females because, after all, only females can reproduce.