As countries become more developed, people naturally have fewer children. Cost of education, opportunity cost to parents' careers, expensive housing, etc. Every developed country sees a steep decline in fertility, from 4-5 children per woman in the developing years to below 2 by the time the country becomes well developed.

I believe a few developed countries in Europe have been able to raise their fertility rate from below-replacement rate of 1.4 to replacement rate of 2.0. I haven't studied exactly how this was done, but I think it involved lots of financial incentives to have and raise children - very liberal parental leave, free child care, free and good education, etc. I don't really see China going in that direction, but I'm not sure.

In the US, our large and relatively cheap houses help maintain larger family sizes. Not speaking of SF or NYC of course, but of much of the country. US fertility rate is about 2.

Russia offers $12,500 USD to have a 2nd child.

Other countries:

6 Creative Ways Countries Have Tried to Up Their Birth Rates | Mental Floss

I like to believe that people are the same worldwide. Please stop with this thinking that "other" parents kill their kids in buckets by the millions. That kind of thinking opens the door to lots of other thinking.

I have read that many of these girls are off the books, not officially registered, so that parents could have another child. Then the boy is registered so he can be educated. That sounds much more likely to me. Especially since the counts of boy/girl ratio imbalance comes from official statistics of registered children.

;)

https://www.soylent.com

I saw a news report several years ago like 60 Minutes where they went to a small village in China and found very lopsided boy to girl ratios. They interviewed the boys about what they were going to do to find wives and the boys were under the impression that there must be villages that were mostly girls just like they were mostly boys and they could find a wife there :rolleyes: