Study: Early Fetal Testing May Be Safe

For years, doctors have used amniocentesis to determine if a fetus is healthy, but that can't be done until the second trimester of pregnancy. Testing in the first trimester was considered dangerous.

Now thanks to improved doctor experience and better technology, a new study says a first-trimester genetic test called CVS is just as safe as amniocentesis.

Dr. Catherine Spong, a physician with the National Institutes of Health, said that in a CVS, a doctor takes a sample of the developing placenta instead of amniocentesis, in which the doctor is taking the amniotic fluid that surrounds the baby. CVS is done between the first 10 to 13 weeks, Spong said.

"Where amniocentesis is typically done between 16 and 20 weeks of gestation," Spong said. "Both of these tests can look at the chromosomes of the baby. In addition, they can look at specific DNA tests or genetic tests, if they're appropriate for the family. Amniocentesis can also evaluate for neural tube defects or spinal bifida."

The new study says that the risk for both procedures has decreased drastically. Now that CVS is considered safer, Spong said women should not fear miscarriages as much as they once might have.

"The risk for both tests has decreased substantially," she said. "In this study that's just come out today, the risk is around 1 out of 360, where it used to be considered 1 in 100 or 1 in 200 at risk."

Spong, an OB/GYN, said a study on amniocentesis last year showed the risk for that procedure may be only about 1 in 1,000 women.

According to Spong, physicians are getting more experienced at doing the tests and technology is improving.

"The ultrasounds are easier to see now, and it's easier to guide these procedures," she said.

Nevertheless, the procedures still present risks: miscarriage, spotting or bleeding, infection and breaking the amniotic fluid sac.

"A woman interested in these procedures should talk to the physician not only about these risks, but consider prenatal screening tests that can further modify what her overall risk of having conditions and the need for doing one of these invasive tests," Spong said.