blood test for pregnancy gender?

NIPT (Noninvasive prenatal testing)
Karen Miles
By Karen Miles
| animated_fact_check Medically reviewed by Layan Alrahmani, M.D., ob-gyn
| March 16, 2022

The NIPT test is a noninvasive blood test that's available to all pregnant women beginning at 10 weeks of pregnancy. It screens for Down syndrome and some other chromosomal conditions, and it can tell you whether you're having a boy or a girl. NIPT is a screening test, so it's not definitive. If NIPT indicates a possible problem, experts recommend having CVS or amniocentesis to be sure.
close up of blood draw
Photo credit: iStock.com / chee gin tan
IN THIS ARTICLE

What is NIPT?
Benefits of NIPT
Is the NIPT test conclusive?
How does the NIPT test work?
What does NIPT screen for?
What does NIPT not screen for?

What is NIPT?

NIPT (noninvasive prenatal testing) is a blood test used to screen for Down syndrome and a few other chromosomal conditions. (It doesn't test for all chromosomal disorders.) NIPT is also known as cell-free DNA screening (cfDNA). Or you may have heard it called MaterniT21, a brand name.

The test is available to all pregnant women, and some healthcare providers offer it to all of their patients. The cost varies widely, but most insurance plans cover at least a portion of the fee.

Some labs will use the NIPT to screen for additional conditions. Work with your provider or a genetic counselor to decide which conditions you want your baby to be screened for. While NIPT screening for some conditions is very accurate – and very helpful for many families – some of these added tests have high inaccuracy rates.
Prenatal test: Chorionic villus sampling (CVS)
2:33 min
CVS is a prenatal test used to diagnose many conditions. Learn what it tests for, what to expect during the procedure, and how long it takes to get results.
Benefits of NIPT

NIPT is a simple procedure that provides a lot of useful information. There are some good reasons why it's such a popular test:

It's not invasive. A simple blood draw taken at a regular prenatal checkup is all you need. There's no need to schedule and take the time for an invasive procedure, like amniocentesis or CVS.
It's perfectly safe for you and your baby and carries none of the potential risks of some other testing. (Amniocentesis and CVS carry a small risk of miscarriage, for example.)
While you'll need follow-up diagnostic testing to confirm results, negative results provide a high degree of accuracy – and reassurance – for a number of conditions.
It's available very early in pregnancy, at 9 to 10 weeks or later.
Results are provided fairly quickly (within a couple of weeks, often sooner).
If you want to know, the test can tell you if you're having a girl or a boy.

Is the NIPT test conclusive?

No, NIPT is a screening test, not a diagnostic test. That means the results don't indicate for sure whether your baby has a chromosomal condition. So, a "normal" NIPT result doesn't guarantee a healthy baby, and an "abnormal" result doesn't mean your baby definitely has a certain condition.

That said, when testing for the major conditions (see below), the NIPT test is very accurate – especially if you get a negative result.

For example, when testing for Trisomy 21 (Down Syndrome), the negative result accuracy of the test is 99.5 percent. If you get a negative result, there's less than a 1 percent chance that it's incorrect. For Trisomy 18, the negative result accuracy is 97.7 percent, and for Trisomy 13 it's 96.1 percent. If you get a negative result for these conditions, there's a high likelihood that the test is correct and you can feel fairly confident that you don't need any further testing.

If you get a positive result, however, the accuracy is less reliable. That means you could get a "false positive" result that would be concerning and might lead you to have additional testing. For Trisomy 21, the chance of a positive result being correct ranges from 33 percent to 83 percent. (The accuracy range is a bit lower for Trisomy 18 and Trisomy 13.) Your more likely to get a false positive if you're at low risk of having a baby with a chromosomal condition. (Risk depends on factors such as your age and whether you have another child with the condition.)

Occasionally (from 1 to 5 percent of the time) a test doesn't yield a result, perhaps because of insufficient fetal DNA in the sample taken. Your provider can review your options with you if this happens.

The NIPT may be less accurate for you if you: