What to Expect: First Trimester Screening
Many of my friends call me in a panic the night before their first trimester prenatal visit to their OBGYN, asking me if they should do the “Down syndrome test.” To be clear, the test they are referring to is the first trimester screen (FTS), which is a test that calculates the risk for the baby to be affected with Down syndrome and two other lethal chromosomal abnormalities (trisomy 18 and trisomy 13). This test consists of an ultrasound measurement of the back of the baby’s neck (AKA the nuchal transulency) and a blood test from the mother, at 11-12 weeks of pregnancy. What I tell my friends is that each person is different and the choice to do or not to do an FTS is entirely dependent on how they feel about it. Here are the facts you should know before making the decision:
1) FTS is a screening test. It is not a diagnostic test. This means that it will not tell you for sure whether or not the baby is affected. Rather, the results will tell you what the chance is that the baby is affected. To find out for sure, you would have to do a more invasive test (ie, CVS or amniocentesis). These invasive tests come with a slight risk of miscarriage.
2) Every single woman who is pregnant has a chance for her child to have a chromosome problem. Her ethnicity, her family history, and her past pregnancies have no effect on this. We do know that as women get older, they are more likely to have a baby with a chromosome problem—but it can happen to anyone.
3) Think about what you would do with the information once you got it. If your FTS showed a high risk for Down syndrome, you would be faced with the decision of doing additional, more invasive testing. If you would consider more invasive testing, , then yes, you should do the FTS. However, if you know that you would not do an invasive test, because of the risk of miscarriage, fear of the discomfort, or because you have religious beliefs against it, then is it really worth it to stress yourself out about the FTS? If the results come back with a low risk, then yes, in retrospect, it is worth it. But if the results show a high risk, then you will spend the remainder of your pregnancy worrying. Of course, you won’t know if it was worth it until you get the results. Hindsight is 20/20…
4) It does not make a difference which one of your friends has done the FTS and which ones have not. Many people ask me if I had an FTS when I was pregnant and my response is, “why should it matter?” We each have our own beliefs and emotions and we should not be basing our decisions on what our friends did. Think about how you feel about these issues and use your own judgment to decide what route is best for you.
So think about it. Is this the right test for you?