Down Syndrome Screening In Pregnancy. For women 35 years or older, maternal serum screening can provide an individual estimate of the likelihood of fetal trisomy 21.15 however, the. A blood test looks for what doctors call “markers,” meaning proteins, hormones, or other substances that could be a sign of down syndrome.

Screening tests provide you with a ratio that expresses your baby's chances of having down syndrome, based on your test results and how old you are. The blood test is free; Thus, pregnancies identified as ‘high risk’ using these screening tests require further testing using amniocentesis or cvs to confirm a diagnosis of down’s.