Pregnant people have many choices when it comes to prenatal genetic testing. Some tests are invasive, and they have a risk of miscarriage. But non-invasive tests carry far fewer physical risks to the pregnant person or the fetus.
Non-invasive prenatal testing (NIPT) is a way to determine the risk of a baby having certain genetic conditions. Extra or missing chromosomes cause these conditions.
What Is the NIPT Test?
NIPT is a screening test that has been around since 2011. It involves taking a small amount of blood from the pregnant person and analyzing it for fragments of DNA.
Most DNA is inside our cells, but we also have tiny pieces of free-floating DNA in our blood, called cell-free DNA. Cell-free DNA is the remnants of cellular genomes that end up in the blood when cells die and break down.
Pregnant people have DNA from their cells and cells in the placenta. Placental cells contain the fetus’ DNA. Analyzing the fetal DNA from the mother’s blood is how doctors can test for potential genetic conditions of the fetus.
NIPT is non-invasive because it poses no physical risk to the fetus. Pregnant people can usually get the test around 10 weeks. Until then, there typically isn’t enough cell-free DNA from the placenta in the pregnant person’s blood.
Which Genetic Conditions Does NIPT Screen For?
NIPT screens for trisomy 21 (Down syndrome) and other chromosome abnormalities, including trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome). It can also screen for extra or missing copies of the sex chromosomes (the X chromosome and Y chromosome). The test analyzes the X and Y chromosomes and can also tell the fetus’s sex.
The American College of Obstetricians and Gynecologists says that NIPT is the most sensitive and specific screening test for these genetic conditions. However, it isn’t 100% accurate and has the potential for false-positive and false-negative results.
The NIPT results tell you if the fetus is at an increased risk of these genetic conditions. You’ll need diagnostic testing to know if the fetus has any of them. Diagnostic testing is more invasive and carries more risks.
Researchers are testing how useful NIPT screenings are for other genetic conditions. These include inherited diseases caused by variants in single genes.
As researchers learn more, doctors will likely be able to offer NIPT to screen for various genetic conditions. However, a 2022 analysis from the New York Times found that NIPT was highly inaccurate for certain rare genetic conditions.
Should I Get NIPT?
ACOG previously recommended NIPT only for people 35 and older or with other known genetic risk factors. But in 2020, they revised their recommendations and said it should be available to any pregnant person.
The current ACOG policy says: “Prenatal genetic screening and diagnostic testing options should be discussed and offered to all pregnant patients regardless of maternal age or risk of chromosomal abnormality. After review and discussion, every patient has the right to pursue or decline prenatal genetic screening and diagnostic testing,”
Because NIPT is an option doesn’t mean it’s the right choice for every family. Instead, it only means that doctors should offer it to every pregnant person.
Whether or not to get NIPT is a personal choice. No one can tell you the right answer for you and your family. Here are some things to keep in mind about NIPT:
- Not accurate for all genetic conditions: It can only accurately screen for a handful of conditions. Negative results (that is, results that don’t show risk for any of the conditions) can’t guarantee a healthy baby.
- Screening, not diagnostic: Cell-free testing is preliminary, not conclusive. If the cell-free results are positive, your doctor will recommend that you get an amniocentesis or chorionic villus test. Both of these tests carry a small risk of miscarriage.
- Knowledge can help you prepare: Knowing about potential genetic disorders can help you decide about your pregnancy and birth plan. It may influence which hospital you choose for delivery. It will also help your care team gather specialists your baby may need.
- Genetic counselors can help: If NIPT and diagnostic results return positive for a genetic condition, talking to a genetic counselor can be very helpful. You shouldn’t have to be alone with the information.