Sex-selective abortion is the practice of terminating a pregnancy based upon the predicted sex of the infant. The selective abortion of female fetuses is most common where male children are valued over female children, especially in parts of East Asia and South Asia particularly in countries such as People's Republic of ChinaIndia and Pakistanas well as in the Caucasusand Western Balkans. Sex selective abortion was first documented in and became when is a fetus sex determined
by the late s in South Korea and China. Sex-selective abortion affects the human sex ratio —the relative number of males to females in a given age group,   with China and India, the two most populous countries of the world, having unbalanced gender ratios. Studies and reports focusing on sex-selective abortion are predominantly statistical; they assume that birth sex when is a fetus sex determined
overall ratio of boys and girls at birth for a regional population, is an indicator of sex-selective abortion. This assumption has been questioned by some scholars. Scholars who support the assumption, suggest that the expected birth sex ratio range is to males to females at birth.