NIPT Results

NIPT is meant to give you more information about whether certain chromosomal conditions are present.

If one of these conditions is present, NIPT usually indicates a higher chance—often reported as “positive” or “detected.” If the condition is not present, the result typically shows a lower chance, or “negative”/“not detected.” In rare cases, NIPT results may not be reported, known as a “test failure.” When this happens, a second blood sample may be collected to repeat the test, although another failure can still occur. If NIPT fails twice, a detailed ultrasound and diagnostic testing, such as chorionic villus sampling (CVS) or amniocentesis, may be recommended.

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Will my NIPT result be accurate?

NIPT has the highest detection rate of all currently available chromosomal screening tests.

The percentage of time a test finds a condition when it is present is called the
 “detection rate“.  A higher detection rate means the test is more likely to find the condition if it is present.

For example, if a test has a detection rate of 99%, it would find 99 out of 100 pregnancies with the condition.

NIPT will detect:

  • 9,970 of 10,000 (99.7%) cases of Down syndrome
  • 9,820 of 10,000 (98.2%) cases of Edwards syndrome
  • 9,900 of 10,000 (99.0%) cases of Patau syndrome

In comparison, first trimester screening will detect 9,000 of 10,000 (90%) cases of Down syndrome and quad screening will detect 8,100 of 10,000 (81%) cases of Down syndrome

What is a positive NIPT result?

A positive NIPT result does not mean the pregnancy is affected. In some cases the condition may not be present. This is called a false positive result. Fewer women receive a false positive result with NIPT compared to other chromosomal screening tests. Results should be confirmed by diagnostic testing (for example, CVS or amniocentesis) prior to making any pregnancy management decisions.

NIPT results are rarely false positive:

  • 4 in 10,000 (0.04%) of women receive a false positive result for Down syndrome
  • 4 in 10,000 (0.04%) of women receive a false positive result for Edward syndrome
  • 4 in 10,000 (0.04%) of women receive a false positive result for Patau syndrome

In comparison, about 400 in 10,000 (4%) of women will receive a false positive result from first trimester combined screening.

The chance that your pregnancy would actually have a chromosomal condition if you receive a positive NIPT result depends on your specific risk factors and should be discussed with your health specialist.

What is a negative NIPT result?

A negative NIPT result means the chance that the condition is present is lower. In rare cases, a screening test may be negative even if the chromosomal condition is present in the pregnancy. This is called a false negative result. 

It is very rare for NIPT to miss finding a pregnancy with a chromosomal condition:

  • Only 30 of 10,000 (0.3%) pregnancies with Down syndrome will be missed
  • Only 180 of 10,000 (1.8%) pregnancies with Edward syndrome will be missed
  • Only 100 of 10,000 (1.0%) pregnancies with Patau syndrome will be missed

In comparison, first trimester combined screening will miss 1,000 of 10,000
(10%) of pregnancies with Down syndrome and quad screening will miss 1,900 of 10,000 (19%) of pregnancies with Down syndrome.

The chance that your pregnancy would not have a chromosomal condition if you receive a negative result depends on your specific risk factors and should be discussed with your health specialist.

Compare First Trimester Screening and NIPT

Choose your age (or age of egg donor):

Out of 10,000 pregnant women, 9987 will have pregnancies without Down syndrome and only 13 will have pregnancies with Down syndrome.

In some cases, a screening test result may show the pregnancy to be at increased risk for Down syndrome, even though the pregnancy is not affected (false positive result).

Of the 13 pregnancies with Down syndrome, FTS would find 12 and miss 1 and NIPT would find 12 or 13 and miss 1 or fewer.

Out of 10,000 pregnant women, 9984 will have pregnancies without Down syndrome and only 16 will have pregnancies with Down syndrome.

In some cases, a screening test result may show the pregnancy to be at increased risk for Down syndrome, even though the pregnancy is not affected (false positive result).

Of the 16 pregnancies with Down syndrome, FTS would find 14 and miss 2 and NIPT would find 15 or 16 and miss 1 or fewer.

Out of 10,000 pregnant women, 9971 will have pregnancies without Down syndrome and only 29 will have pregnancies with Down syndrome.

In some cases, a screening test result may show the pregnancy to be at increased risk for Down syndrome, even though the pregnancy is not affected (false positive result).

Of the 29 pregnancies with Down syndrome, FTS would find 26 and miss 3 and NIPT would find 28 or 29 and miss 1 or fewer.

Out of 10,000 pregnant women, 9917 will have pregnancies without Down syndrome and only 83 will have pregnancies with Down syndrome.

In some cases, a screening test result may show the pregnancy to be at increased risk for Down syndrome, even though the pregnancy is not affected (false positive result).

Of the 83 pregnancies with Down syndrome, FTS would find 75 and miss 8 and NIPT would find 82 or 83 and miss 1 or fewer.

Out of 10,000 pregnant women, 9678 will have pregnancies without Down syndrome and only 322 will have pregnancies with Down syndrome.

In some cases, a screening test result may show the pregnancy to be at increased risk for Down syndrome, even though the pregnancy is not affected (false positive result).

Of the 322 pregnancies with Down syndrome, FTS would find 290 and miss 32 and NIPT would find 321 or 322 and miss 1 or fewer.

Please note: This indicates the age-related chance for Down syndrome at 10 weeks gestation. The chance for other chromosomal conditions is in addition to this chance. The chance for a chromosomal condition in your pregnancy may vary based on your family history, clinical history, and any previous screening results. Please speak to your health specialist for your specific chances.

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