# The 67 million baby girls

I’m interested in ultra-high (male-to-female) sex ratio at birth in China and hence I went to compute how many more baby girls could have been born between 1980 and 2015, assuming a “normal” sex ratio at birth. I will briefly explain my method based on the UN data, and then explain why the estimated figure has upward bias.

Based on the UN data, the sex ratio in China has steadily increased from 1.07 in first half of 1980s to 1.16 in the first half of 2000s. For the same period, the world sex ratio stabilized between 1.06 and 1.08, while the one for less developed regions (excluding least developed regions) increased moderately from 1.06 to 1.09.

Based on the UN data, over the past 35 years, around 363 million baby boys and 323 million baby girls were born in China, with average sex ratio at birth at 1.12.

What should be a “normal” sex ratio at birth in China? There probably won’t be an accurate answer, but let’s try to use make some assumption. It makes little sense to assume the ratio to be 1.0, given the world average is 1.07. It probably also does not make sense to compare China against DMs, as wealth level might influence sex ratio at birth. It may not be unreasonable to use the average of less developed countries (excluding least developed countries) as proxy, as China belongs to this group. Applying this proxy as the “normal” sex ratio at birth – which is lower than the actual ratio for China – onto the number of baby boys that were born in China, I have found that additional 67 million baby girls could have been born over the past 35 years, or average 1.9 million per year.

There are a few reasons why this figure has upward bias:

• If Chinese parents had less gender bias, then maybe fewer boys would have been born, as fewer families would have tried to have a boy when their first child (or first few children) was a girl.
• A baby girl may have been less likely to be registered to the local government than a baby boy does. Hence the reported UN figure may have under-reported the number of baby girls that were actually born.

Btw, please do not use this figure as an approximate number of baby girls killed via abortion. Even without abortion, gender bias of some Chinese parents would also result in a sex ratio at birth higher than other countries.