Down Syndrome Pregnancy Testing. In the case of down syndrome, the child receives an extra of chromosome 21, for a total of three. For the first 24 weeks of pregnancy, the evidence does not support the use of urine.

The test measures the amount of four proteins in the mother’s blood (alpha. For the first 24 weeks of pregnancy, the evidence does not support the use of urine. Chorionic villus sampling (cvs) is the test used to identify down’s syndrome.