NIPT Test: When You Can Have It, How Accurate It Is and What It Shows

What is the NIPT test?

NIPT (noninvasive prenatal testing) is a blood test, possible from 10 weeks of pregnancy, that screens for Down syndrome and some other chromosome conditions by looking at DNA from the placenta in your blood. ACOG calls it cell-free DNA testing and says it can screen for Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13) and problems with the number of sex chromosomes.

MedlinePlus Genetics, from the US National Library of Medicine, explains that the placenta sheds DNA into your bloodstream and that this DNA is usually identical to the baby's. Because only your blood is taken, MedlinePlus says the test poses no risk to the baby.

NIPT is a screening test. MedlinePlus says it estimates whether the risk of certain conditions is increased or decreased and cannot give a definite answer.

The US and the UK use NIPT at different points in pregnancy care.

When can you have the NIPT test?

You can have NIPT from 10 weeks of pregnancy. MedlinePlus Genetics explains why: more than 4% of the DNA in your blood generally has to come from the placenta, and that level is typically reached around the tenth week. Cleveland Clinic says the test can be done from 10 weeks up until delivery.

In the US, ACOG's January 2026 practice advisory endorses guidance from the Society for Maternal-Fetal Medicine that cell-free DNA screening for trisomies 21, 18 and 13 be routinely available to all pregnant patients. The advisory also says every patient has the right to have or decline screening after counseling, and lists lack of insurance coverage among the reasons it sometimes cannot be offered.

The NHS in England uses NIPT as a second step. You are offered it after a higher-chance result from the combined test (the nuchal translucency scan plus a blood test) or from the quadruple test. GOV.UK says NHS NIPT is offered up to 21 weeks and 6 days, in single and twin pregnancies.

What does NIPT screen for?

NIPT mainly screens for Down syndrome, trisomy 18 and trisomy 13, and Cleveland Clinic says most NIPTs also screen for conditions of the sex chromosomes. It lists Turner syndrome, Klinefelter syndrome, triple X syndrome and XYY syndrome as the most common of these.

ACOG's 2026 advisory recommends offering sex chromosome screening as an opt-in choice with counseling beforehand. It does not recommend routine screening for microdeletions, which are small missing pieces of a chromosome, and says anyone who wants that information should be offered diagnostic testing instead.

NHS NIPT is narrower. GOV.UK says it screens only for Down's, Edwards' and Patau's syndromes and is not used to find other conditions. Cleveland Clinic says NIPT can't screen for all chromosomal or genetic conditions.

How accurate is NIPT?

ACOG calls NIPT the most sensitive and specific screening test for Down syndrome and trisomies 18 and 13, and MedlinePlus Genetics notes it can still give false-positive and false-negative results. Cleveland Clinic says it detects about 99% of Down syndrome cases and about 97% to 98% of trisomy 18 cases, with fewer false positives than the quad screen.

GOV.UK says at least 90% (9 out of 10) of people with a higher-chance NIPT result for Down's syndrome are carrying a baby who has the condition. It explains one reason the test is not 100% accurate: the DNA comes from the placenta, which in rare cases is not identical to the baby's. MedlinePlus Genetics adds that because NIPT also reads your own DNA, it may pick up a genetic condition in you.

Sometimes NIPT gives no result. MedlinePlus says too little placental DNA in the sample can make the test impossible to run or cause a false negative, and lists testing too early, sampling errors, obesity and a fetal condition as reasons. GOV.UK says no result can happen if your BMI is over 30 or you are having twins, and that NIPT might be less accurate in twin pregnancies.

Can NIPT tell you the baby's sex?

NIPT in the US can usually show the baby's sex chromosomes, while NHS NIPT in the UK does not report the sex. Cleveland Clinic says most NIPTs screen the sex chromosomes, so the test can tell whether XX or XY chromosomes are present, and that this result is highly accurate but not 100% accurate. ACOG recommends offering sex chromosome screening as an opt-in, so ask beforehand what your test will report.

GOV.UK says NHS NIPT will not tell you whether the baby is a boy or a girl. ACOG says the sex may also be visible on the 20-week anatomy scan if the baby is in a good position.

What happens if your NIPT result is high risk?

A higher-chance NIPT result should be checked with a diagnostic test before any decision about the pregnancy. ACOG says a positive cell-free DNA result should be followed by amniocentesis or chorionic villus sampling (CVS), and its 2026 advisory adds genetic counseling and a detailed anatomy scan.

GOV.UK says diagnostic tests give a definite answer and that about 1 in 200 people (0.5%) who have one will miscarry because of the test. CVS is usually done from 11 to 14 weeks and amniocentesis after 15 weeks. Whether to have one is your decision, and so is having no further tests.

A test that gives no result also needs follow-up. ACOG's 2026 advisory says a nonreportable result should lead to an offer of genetic counseling, a detailed ultrasound and diagnostic testing, because it carries a higher chance of a chromosome condition. GOV.UK says you can choose a second NIPT, a diagnostic test or no further testing.

Most people get a lower-chance result. GOV.UK says no diagnostic test is offered after a lower-chance NIPT result, and that some people with a lower-chance NIPT result do have a baby with one of the conditions.

When should you call your doctor or midwife?

• Before the test, if you want to talk through how you would use the result. ACOG says your beliefs and values matter in this decision and that there is no right or wrong answer.
• When you get a higher-chance result or no result, to arrange counseling and discuss diagnostic testing.