The Associated Press is reporting that a new blood test, performed only 9 weeks into a pregnancy, may be able to accurately detect Down syndrome. Current screening for the chromosomal abnormality, which causes serious intellectual and developmental disability, starts with a blood test and is followed by an amniocentesis at four months gestational age.
Amniocentesis, in which a needle extracts amniotic fluid to test for Down syndrome and other diseases, poses a small risk of miscarriage, as does the similar procedure known as CVS (chorionic villus sampling). According to the Boston Globe:
Companies are racing to market a more accurate blood test than those available now that could spare many women the need for the other two tests. It would retrieve fetal DNA from the mother's bloodstream, and the answer could come before the pregnancy is obvious to others.
Current screening has already reduced the number of babies born with the syndrome, which now stands at about 6,000 each year in the United States, or about 1 in every 691 babies, said Dr. Brian Skotko, a Down syndrome specialist at Children's Hospital Boston.