Pregnancy after age 35 can carry a higher chance of fetal autosomal disorders such as Down syndrome, but a new test available at UT Southwestern can screen for the most common types with no risk of miscarriage.
This method, known as cell-free fetal DNA testing, is noninvasive and requires only a simple blood draw from the mother. During pregnancy, cells from the placenta get into the mother’s bloodstream and rupture, releasing fetal DNA into the mother’s blood. The new test isolates the fetal DNA and analyzes it for evidence of the most common autosomal disorders. Its accuracy rate for detecting Down syndrome is 99 percent.
The testing, which can be performed as early as the ninth week of pregnancy, can help determine if an amniocentesis is needed in women with high-risk pregnancies, says Robyn Horsager, M.D., Professor of Obstetrics and Gynecology and a maternal-fetal medicine specialist at UT Southwestern. In addition to maternal age, risk factors for fetal autosomal disorders include fetal abnormalities seen on ultrasound and a previous pregnancy with an autosomal disorder.
“This test allows us to reduce the number of invasive procedures like amniocentesis and chorionic villus sampling in pregnant women over 35 while maintaining a high detection rate for the most common chromosome abnormalities,” Dr. Horsager says. “This then lowers the risk of miscarriage, which is obviously a high priority for patients and obstetricians.”
The new William P. Clements Jr. University Hospital, opening in November, will let doctors and patients manage high-risk deliveries in a state-of-the-art setting with single-patient neonatal intensive care unit rooms, she notes.