While most pregnant women get non-invasive genetic testing to screen for chromosomal abnormalities in their fetuses such as Down syndrome, some might choose to skip the testing if they were fully informed about the upsides and downsides.
In a new study involving 710 pregnant women that was published in the Journal of the American Medical Association, researchers found that those who were shown an interactive computer program educating them about prenatal testing were more likely to skip non-invasive screening blood tests and ultrasounds; they were also more like to skip invasive testing, such as amniocentesis, that involves using a needle to draw DNA-containing fluid from a woman’s womb and carries a small risk of miscarriage.
Nearly 6 percent of the women who used the decision-making tool opted to have invasive testing compared with 12 percent of those in the control group; nearly 26 percent of those who used the program decided to skip prenatal testing altogether compared to 20 percent of those who didn’t.
“Women are supposed to be offered screening and informed about its implications, but there are definitely some who are having this testing without realizing what it is they signed up for,” said study leader Miriam Kuppermann, a professor of obstetrics, gynecology & reproductive sciences at the University of California, San Francisco.
Many may not understand that even a simple blood test — which measures risks of fetal abnormalities — can have drawbacks, causing anxiety if there’s a worrisome result and leading to more invasive and riskier testing to gain more definitive information.
“Timing of the information is very relevant,” said Dr. Siobhan Dolan, a geneticist at Montefiore Medical Center who wrote an editorial that accompanied the study. “Part of decision support tools is to help women determine when is the right time for them? There’s no right answer is the point we might take from it, but I’m delighted there’s a tool out there to help people decide.”
The decision-making program isn’t available yet for doctors to use in clinical practice, but Kuppermann said she hopes to update the program and make it available online within the next year. It was used in the study before a new prenatal blood test — called the cell-free DNA test — became widely available. Research suggests the new test, that examines pieces of fetal DNA, is 10 times more reliable than the older blood test and ultrasound exam that look for certain markers; it can eliminate the need for more invasive testing in women who have a normal result.
Abnormal results, however, still need to be confirmed with amniocentesis or chorionic villus sampling because in more than half of cases where abnormalities are found, no chromosomal abnormality is detected when the full DNA in fetal cells is examined.
“I’ve heard anecdotal reports of women terminating their pregnancies based on a positive result from a cell-free DNA test without having any follow-up testing,” Kuppermann said. In fact, an August study found that 6 percent of women with abnormal results on this test chose to end their pregnancies without having the additional testing to confirm their results.