FROM WIKIPEDIA

Sex-selective abortion is the targeted abortion of a fetus based upon its sex. This is done after a determination is made (usually by ultrasound but also rarely by amniocentesis or another procedure) that the fetus is of an undesired sex. Sex selective infanticide is the practice of selective infanticide against infants of an undesired sex. One common method is child abandonment.
These practices are especially common in some places where cultural norms value male children over female children. Societies that practice sex selection in favor of males (sometimes called son preference or female deselection) are quite common, especially in The People's Republic of China, Korea, Taiwan, Malaysia, India, Pakistan, New Guinea, and many other developing countries in Asia and North Africa; sex selection in favor of females appears to be rare or non-existent, although some legends of Amazons say that they practiced male infanticide. In 2005, 90 million women were estimated to be missing in seven Asian countries alone due, apparently, to prenatal sex selective abortion. However, other reasons for the sex ratio imbalance in certain countries have been proposed. The existence of the practice appears to be determined by culture, rather than by economic conditions, because such deviations in sex ratios do not exist in sub-Saharan Africa, Latin America, and the Caribbean. Sex-selective abortion was rare before the late 20th century because of the difficulty of determining the sex of the fetus before birth, but ultrasound has made such selection easier. However, prior to this, parents would alter family sex compositions through infanticide. It is believed to be responsible for at least part of the skewed birth statistics in favor of males in mainland China, India, Taiwan, and South Korea.