According to the Annual Report on the Vital Statistics, the sex ratio at birth in Korea increased dramatically during the last two decades. In 1980 there were 104 male births for every 100 female births. The sex ratio was 110 in 1985, but became 117 in 1990 and still was 116 in 1995. The rise in the sex ratio at birth is no doubt due to sex-selective abortions and can be verified by comparisons of the sex ratio by parity. Selective abortions occur mostly at high birth orders.
Mothers tend to leave the sex of the first child, and to a lesser extent the second child to chance.
Those who are 'unlucky' in their first two births and have a strong son preference increasingly practice sex-selective abortion. It has been reported that son preference was a barrier to reducing fertility, if parents continued to have children until they reached their desired number and sex composition. However, couples have relatively less control over the sex of their children than they do over the number. The sex ratio at birth in Korea has been positively associated with birth order in recent years. In the early 1980s, the mean sex ratio at birth was within as acceptable range, but increased abruptly from the mid-1980s.