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 China, India and Pakistan), as well as in the Caucasus, Western Balkans, and to a lesser extent North America. Based on the third National Family and Health Survey, results showed that if both partners, mother and father, or just the father, preferred male children, sex-selective abortion was more common. In cases where only the mother prefers sons, this is likely to result in sex-selective neglect in which the child is not likely to survive past infancy.

Sex selective abortion was first documented in 1975, and became commonplace by the late 1980s in South Korea and China and around the same time or slightly later in India.

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 ratio—the 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. Researchers have shown that in India there are approximately 50,000 to 100,000 female abortions each year, significantly affecting the human sex ratio.

According to demographic scholarship, the expected birth sex ratio range is 103 to 107 males to 100 females at birth.