GUIDE
NIPT (non-invasive prenatal testing) is a blood test available from week 10 that screens for chromosomal conditions like Down syndrome with greater than 99% detection rate.
NIPT analyzes fragments of placental DNA circulating in your blood. It is a screening test, not a diagnostic test — a high-risk result should be confirmed with amniocentesis or CVS before making any decisions.
Be prepared from day one
NIPT — also called cell-free DNA screening or cfDNA testing — is a simple blood draw from your arm, available from week 10 of pregnancy onward. It analyzes tiny fragments of DNA from the placenta that circulate in your bloodstream. Because the placental DNA usually matches the baby's DNA, the test can screen for specific chromosomal conditions with high accuracy.
Brand names include MaterniT21, Harmony, Panorama, and informaSeq, but they all work on the same principle. The test is non-invasive (just a blood draw) and carries zero risk of miscarriage, unlike diagnostic procedures such as amniocentesis.
Results typically take 7 to 10 business days. Your provider will discuss the results with you and recommend next steps if anything is flagged.
| Condition | Detection Rate | Specificity | Details |
|---|---|---|---|
| Trisomy 21 (Down syndrome) | >99% | ~97–99% | Most common chromosomal condition. Extra copy of chromosome 21. |
| Trisomy 18 (Edwards syndrome) | 96–99% | ~97–99% | Serious condition with multiple organ effects. Extra copy of chromosome 18. |
| Trisomy 13 (Patau syndrome) | 91–99% | ~97–99% | Severe condition. Extra copy of chromosome 13. |
| Sex chromosome differences | ~95–99% | ~99% | Turner syndrome (45,X), Klinefelter (47,XXY), Triple X, 47,XYY. |
| Fetal sex | >99% | N/A | Detected by presence/absence of Y-chromosome material. |
The difference between screening and diagnostic testing is critical. Discuss your results with your provider or a genetic counselor.
This is the most important distinction to understand. NIPT is a screening test — it estimates the probability that a condition is present. It is not a diagnostic test that gives a definitive yes-or-no answer.
A "low-risk" or "negative" NIPT result is highly reassuring. The negative predictive value for Down syndrome is greater than 99.9 percent, meaning a low-risk result is almost certainly correct.
A "high-risk" or "positive" result is less straightforward. Because NIPT analyzes placental DNA (which usually but not always matches fetal DNA), false positives do occur. The positive predictive value depends heavily on your baseline risk, which is influenced by maternal age. This is why ACOG strongly recommends confirmatory testing — either amniocentesis (after week 15) or CVS (weeks 10-13) — before making any decisions based on a positive NIPT result.
ACOG updated its position in 2020 to recommend that NIPT be offered to all pregnant patients, not just those over 35 or at high risk.
NIPT can be performed any time after week 10 of pregnancy. Most people have it done between weeks 10 and 13, often around the same time as the nuchal translucency scan. Some providers combine these results for a more comprehensive first-trimester risk assessment.
There is no upper time limit for NIPT — it can be done later in pregnancy if you missed the first-trimester window. However, earlier testing gives you more time to process results and make informed decisions about further testing if needed.
Testing earlier than 10 weeks is not recommended because fetal DNA levels may be too low for an accurate result, leading to inconclusive results and the need for a redraw.
Consider meeting with a genetic counselor before the test, especially if you have a family history of genetic conditions. They can explain what the test can and cannot tell you, help you decide which screenings to pursue, and prepare you for possible results.
NIPT results are typically reported as "low risk" or "high risk" for each condition screened. Some labs also provide a risk score (for example, less than 1 in 10,000 for trisomy 21).
If all results are low risk, no further chromosomal testing is typically needed. You will continue with your regular prenatal visit schedule, including the anatomy scan at 20 weeks.
If any result comes back high risk, your provider will recommend a follow-up appointment — often with a genetic counselor — to discuss confirmatory testing options. Remember: a high-risk NIPT result does not mean your baby has the condition. It means the probability is elevated and diagnostic testing is the next step.
For the full picture of what tests happen throughout pregnancy, see our pregnancy blood tests guide and the complete prenatal visit schedule.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
