Taking medical tests that reveal the health of the baby can be stressful for moms-to-be. A recent study may eliminate some of the anxiety. Researchers found that the new first-trimester test for Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18) appears to have a higher degree of accuracy than the standard second-trimester test, known as the triple screen. "This test more accurately predicted abnormalities with fewer false positives," says Ronald Wapner, M.D., chairman of obstetrics and gynecology at Drexel University College of Medicine, in Philadelphia, and lead author of the study. ("False positives" occur when the test suggests an elevated risk of a birth defect when there isn't one.)

The research, published in the New England Journal of Medicine, screened more than 8,000 pregnant women for chromosomal abnormalities using the new test, which consists of an ultrasound to examine the "nuchal measurement" (the amount of fluid in the nape of the fetus's neck; too much can be a sign of Trisomy 21) and a blood test to detect hormone levels associated with the conditions. The test identified 80 percent of the 61 cases of Down syndrome (with a 5 percent false-positive rate) and 91 percent of the 11 cases of Trisomy 18, a fatal defect (with a 2 percent false-positive rate). As a comparison, the second-trimester triple screen identifies between 60 to 65 percent of anomalies and has a 5 percent false-positive rate.

First-trimester testing is available in many U.S. cities; ask your doctor if you're interested in finding a testing center near you.

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