| Down Syndrome |
|Genetic disorder; about 92% of pregnancies in Europe with a diagnosis of Down syndrome are terminated.|
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely.
Down syndrome is the most common chromosomal abnormality in humans. Globally, Down syndrome occurs in about 1 per 1,000 births and results in about 17,000 deaths.  More children are born with Down syndrome in countries where abortion is not allowed and in countries where pregnancy more commonly occurs at a later age. About 1.4 per 1,000 live births in the United States and 1.1 per 1,000 live births in Norway are affected. In the 1950s, in the United States, it occurred in 2 per 1000 live births with the decrease since then due to prenatal screening and abortions. The number of pregnancies with Down syndrome is more than two times greater with many spontaneously aborting. It is the cause of 8% of all congenital disorders.
About 92% of pregnancies in Europe with a diagnosis of Down syndrome are terminated. As a result, there is almost no one with Down's in Iceland and Denmark, where screening is commonplace. In the United States, the termination rate after diagnosis is around 75%, but varies from 61% to 93% depending on the population surveyed. Rates are lower among women who are younger and have decreased over time. When asked if they would have a termination if their fetus tested positive, 23–33% said yes, when high-risk pregnant women were asked, 46–86% said yes, and when women who screened positive are asked, 89–97% say yes.
- Choi, H; Van Riper, M; Thoyre, S (Mar–Apr 2012). "Decision making following a prenatal diagnosis of Down syndrome: an integrative review". Journal of Midwifery & Women's Health. 57 (2): 156–64.