WI shortly after the reports of mass abortions of girls came about, China decided on a two-child policy to fix this instead?
Sort of ambivilient of the chance PRC changing due to foreign opinion. If they did, remember that the one child policy is only for the quarter who live in the cities. The rest can have two if the first is a girl, or in the case of of minorities (Tibetans, Southern Chinese tribes, Mongolians, etc.) 8% or so of the pop if recalled right, there is no limit IOTL.
In this case, the cities remain easier to limit. The immigrants are young adults and eager for an easier life than the tough countryside. At one child, the cities become needing new blood. Also, in the cultural revolution many city dwellers were sent permanently sent to the country, and never could get legal permission to return.
Change that and you could have worse Tianamen Square difficulties, etc.
http://en.wikipedia.org/wiki/One-child_policy