These tests will tell you what the chances are for your baby having Down syndrome and Trisomy 18.
Down syndrome is the most common chromosome disorder. It is caused by the fetus having an extra chromosome 21. It commonly results in some degree of mental retardation, heart abnormalities, and other birth defects. The chance of having a child with Down syndrome is about 1 in 800 for all women, but it is higher for women who are over 35 years of age.
Trisomy 18 is caused by the fetus having an extra chromosome 18. It results in severe mental retardation and physical abnormalities. The general risk of having this is about 1 in every 1000 pregnancies, but as your age goes up, the risk also goes up. A very high number of babies with Trisomy 18 die before their first birthday.
The decision to have the test done is left up to you.
The test involves a simple blood test and a special ultrasound. The blood is taken from a vein in your arm or by pricking your finger at 11-13- 6/7 weeks into your pregnancy. The blood test measures 2 different chemicals. The special ultrasound, called NT, measures the amount of fluid behind the fetus’ neck. The NT ultrasound must be done at an office that is qualified to perform this service and must be done along with the blood testing.
The test will find 85%-91% of Down syndrome and about 95% of Trisomy 18. The results will available in about 1 week.