A snot-nosed grad student from Berkeley pointed out that hepatitis B couldn't possibly explain the missing women problem. It turned out Asian women gave birth to daughters at the same rate as women everywhere else, at least during their first pregnancy. It was only during subsequent births that the ratios changed. Either a bunch of Asian women were running out to get hepatitis B in between their first and second pregnancies, or, as Sen feared, people were taking dramatic steps to avoid ending up with two girls.

You seem to take this TNR claim at face value but I don't think this is a correct presentation of what actually happened.