If a couple chooses to test for genetic defects in their unborn baby, they must go through a series of invasive procedures that can be potentially risky to the fetus and the mother. Amniocentesis, which typically tests for Down’s Syndrome, cystic fibrosis, and spina bifida at around 20-weeks of pregnancy, tests the amniotic fluid around the baby by inserting a needle into the mother’s belly. Chronic villus sampling tests tissue from the placenta and can be done earlier in the pregnancy at around 10-weeks. Both test have their risks to mother and baby and can only detect a small number of genetic abnormalities.
However, a new test, using blood and saliva samples from the mother and father, can now detect up to 3,500 genetic disorders without posing a risk of miscarriage to the pregnancy. Not only do blood tests pose less risk, but they are also more accurate. As the fetus’ DNA crosses the placenta, it goes into the mother’s bloodstream where it can be detected. Down’s Syndrome, caused by an extra copy of chromosome 21, can be detected when there is an excess of chromosome 21 in the mother’s bloodstream.
For families who opt for prenatal testing, this promises to be a safer alternative to the traditional prenatal tests.