First of all, how come the Chinese fertility rate did not decline substantially until 1990? Was the OCP only enforced on a small and experimental scale until the 90s started?
Is this why there was an enormous drop in fertility rate between 1990 and 1991 from 2.6 to 1.8, or did that have more to do with people not wanting to have (or now being forced not to have) kids after Tiananmen Square? That happened in June of 1989 so if it influenced people's choice not to have kids it would have started making birth rates fall in March 1990. Was sex selective abortion pretty minimal before this? Because the stats suggest the post-80s actually have an improved sex ratio compared to the people born in the 60s and 70s and the male surplus wasn't atypical of Chinese history until the mid to late 90s.
And lastly, what is the cause of the missing girls? Is it overwhelmingly selective abortion, was murder a substantial factor, or were most of the missing girls born but just uncounted and denied an education or adopted overseas? Or is it a fairly equal combo of all these things?
Hi there. I can answer some of your questions, but not all of them so I'll try to the best of my ability.
The One Child Policy was born from an experiment in the 1970's where it was enforced only two children were allowed per home in various provinces. Surprisingly, the policy was well-received. There was a huge burden on resources like water and food that caused this policy to be enacted.
The One Child Policy was enacted between 1978 and 1980 depending on the province. One thing to keep in mind is that not all provinces enacted the policy, and the policy didn't apply to every citizen. For example: if both parents were only child in their families then they could have two children. Even this exemption was based on the province you lived (Xinjiang and Tibet were those not accepting of this policy). Needless to say, there was a lot of flexibility on the policy depending on various circumstances.
Chinese culture has a strong bias towards paternal lineage. This is very true today. There are a lot of women's rights activities going on in the mid-80s-90's similar to what the US went through decades previously. It's still a strongly male dominant society compared to the Western world, but a lot more relaxed since 1980's. Thus, it was mostly preferred that if a couple was to have a child, it was going to be a male. If the couple had a daughter and became pregnant again, then delivered a boy, the daughter would be.. Well, abandoned, put up for adoption, sold for sex, etc. Plus, there was the influence of ultrasonography technology and couples could abort the child if they knew it was a female, or they just didn't record their births officially.
So to answer your question about male surplus in the late 90's: People aren't looking for mates until they're typically about 18. 2000-18 and you're looking at the early-80s, right in the midst of the policy. This would explain why the gap doesn't appear until the late 90's, because that's when they were of age to marry.
During the late 80's there was economic reform, better education, migration from farmland to cities, etc. This may explain the spike you're seeing in 1990. My guess you saw this graph from Wikipedia. However, it's closer to this graph from this study.
It was specifically designed to be enforced for one generation. As we know, that didn't necessarily pan out as planned. But, the policy was very effective.
