Down syndrome and other birth defects can be detected earlier and with greater accuracy, a new study shows.
The study, published Wednesday in the New England Journal of Medicine, was led by a team of doctors and scientists around the country, including Dr. David A. Nyberg, director of the Fetal and Women’s Center of Arizona in Scottsdale.
The study, involving nearly 40,000 pregnant women at 15 centers nationwide, examined the effectiveness of screening the fetus in the first tri- mester.
The results could lead to a change in standard medical practice. Screenings could be done by the time a fetus is about 12 weeks old, instead of waiting until the second trimester.
It also means women carrying babies with abnormalities could get help earlier. In some cases, doctors could do an inutero surgery or treatment, addressing the baby’s health problems in the womb instead of after delivery, Nyberg said.
Many doctors conduct ultrasounds and other tests during the second trimester to check the baby’s health.
But the study, in which doctors focused on checking for Down syndrome, shows that there are fewer false-positive results when screenings are done in the first trimester.
Accuracy in first trimester screening is nearly 90 percent -- about 5 percentage to 10 percentage points higher than in the second trimester.
Accuracy is just one benefit of early screening. The other, Nyberg said, is safety.
Doctors are trying to steer away from screening fetuses through invasive procedures, such as genetic amniocentesis, in which a needle draws out fluid from the womb to be examined for Down syndrome and other abnormalities. Such a procedure has a risk of harming the fetus.
"To get the fluid, we have to go through the membrane," Nyberg said. "Because of that, we breach the membrane, and sometimes fluid can leak out."
That fluid is crucial for a healthy pregnancy, providing the baby with cushion and freedom to move in the womb. It also holds the proteins, carbohydrates and fats necessary for the fetus to grow.
Another more common and popular method, ultrasound "is safer because there is no risk involved," Nyberg said. The technology relies on using sound to produce images of the fetus.
Most pregnancies are healthy, but about 3 percent to 5 percent of fetuses have some defect. Ten percent of babies with abnormalities are afflicted by a chromosomal defect, such as Down syndrome.
While discovering a health problem in the baby can come as a shock to parents, the earlier they know, the earlier they can cope and plan for the challenges ahead, said Dr. John Stock, a Phoenix pediatric cardiologist
If a patient waited to find out about her baby’s health condition, the discovery, after an emotional and physicallyexhausting labor, would be devastating.
"You go to sleep dreaming of this baby that has 10 fingers and 10 toes," Stock said. "But having a baby with a heart defect, people face a grieving process. Sometimes it’s better to go through that process (early)."
Routine screening also helps doctors assure parents that their babies are healthy — critical for high-risk patients who have had miscarriages or are at a high risk of complications.
Stephanie Vonbank is 49, and expecting twins -- a boy and a girl. The combination of her age and bearing twins are factors that raise her risk of problems. The Ahwatukee Foothills woman would have had children earlier in life, but "I just met my prince five years ago."
But Vonbank said she’s "fit as a fiddle," and routine ultrasounds have assured her and her husband, Michael, that their babies are healthy.
"It’s brilliant," said Vonbank, a flight attendant for America West. "You can lie there and see your kiddies growing. They tell you if there’s complications. You have a week-to-week diary of what they’re doing."
Doctors will have to induce labor soon, since Vonbank is at 38 weeks. She expects to be holding and nursing newborns within days.