What makes this social change — where parents, especially in East and Southeast Asia, previously heavily favored having male children and now much less so — extra surprising is that many of the technological factors that drove the gender selection preference (such as access to early gender testing and IVF) have dramatically improved over time.
The fading of boy preference in regions where it was strongest has been astonishingly rapid. The natural ratio is about 105 boy babies for every 100 girls; because boys are slightly more likely to die young, this leads to rough parity at reproductive age. The sex ratio at birth, once wildly skewed across Asia, has become more even. In China it fell from a peak of 117.8 boys per 100 girls in 2006 to 109.8 last year, and in India from 109.6 in 2010 to 106.8. In South Korea it is now completely back to normal, having been a shocking 115.7 in 1990.
