A 2005 study estimated that over 90 million females were "missing" from the expected population in Afghanistan, Bangladesh, China, India, Pakistan, South Korea and Taiwan alone, and suggested that sex-selective abortion plays a role in this deficit.[2][3] India's 2011 census shows a serious decline in the number of girls under the age of seven - activists fear eight million female fetuses may have been aborted between 2001 and 2011.[4] Some research suggests that culture plays a larger role than economic conditions in gender preference and sex-selective abortion, because such deviations in sex ratios do not exist in sub-Saharan Africa, Latin America, and the Caribbean.[2] Other demographers, however, argue that perceived gender imbalances may arise from the underreporting of female births, rather than sex-selective abortion or infanticide.[5][6][7]
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. Prior to this, parents would alter family sex compositions through infanticide.
[edit] Practical aspects
Sex detection can be performed by the means of one of the two standard genetic tests, CVS and amniocentesis. These may, in principle, be performed as early as the 8th and the 9th week of pregnancy. The difficulty of these tests and the risk of damage to the fetus, potentially resulting in miscarriage or congenital abnormalities (especially when done early during the