Points cles
- The earliest possible time for NIPT is week 10 of pregnancy — before this, fetal fraction is typically too low for reliable results
- The optimal window is weeks 10-13, allowing results to arrive alongside your NT scan findings for a comprehensive first-trimester picture
- NIPT can be done at any time after week 10 — there is no upper limit, and some women choose to test in the second trimester
- Testing too early (before week 10) increases the risk of low fetal fraction, which may result in an inconclusive test requiring a redraw in 1-2 weeks
- Results typically take 5-10 business days, so a blood draw at week 10-11 means results are available by week 11-13 — aligning perfectly with first-trimester decision-making
Timing matters when it comes to NIPT. Test too early, and you risk an inconclusive result that wastes time and money. Test too late, and you miss the opportunity to have chromosomal information when you need it most — during the first-trimester screening window when all prenatal decision-making is most straightforward. The good news is that the optimal window is clear and well-supported by evidence. This guide explains exactly when to schedule your NIPT test, how timing affects accuracy, and how NIPT fits into your broader first-trimester screening timeline.
The question of "when" to do NIPT is really three questions: when is the earliest I can test, when is the best time to test, and what happens if I miss the ideal window? Each has a clear, evidence-based answer. This guide also addresses the relationship between NIPT timing and your nuchal translucency scan, combined first-trimester screening, and results turnaround — so you can plan your entire first-trimester screening schedule with confidence.
Earliest Possible: Why Week 10 Is the Starting Line
NIPT analyses cell-free fetal DNA (cffDNA) circulating in the mother's bloodstream. This fetal DNA is released into the maternal circulation by the placenta, and its concentration — called the fetal fraction — increases progressively as the pregnancy advances and the placenta grows. At 7-8 weeks, fetal fraction is typically only 2-3%, which is below the minimum threshold of 4% required by most laboratories. At 9 weeks, it rises to approximately 3-5% — borderline for reliable analysis. By week 10, the average fetal fraction reaches 7-10%, comfortably above the threshold for all major NIPT platforms.
This is why every major NIPT guideline and every NIPT laboratory specifies 10 weeks as the minimum gestational age for testing. Attempting NIPT before week 10 significantly increases the risk of receiving a "no call" or "test failure" result — meaning the laboratory could not extract enough fetal DNA from the blood sample to produce a reliable result. A no-call result is not harmful, but it wastes time (1-2 weeks waiting for the failed result) and money (though most laboratories will re-run the sample at no additional charge if fetal fraction was too low).
The gestational age used for NIPT timing should be based on either your last menstrual period (LMP) or, more accurately, on your dating ultrasound measurement. Because some women have irregular cycles, the actual gestational age may differ from the LMP-calculated age by a week or more. If your dating scan shows you are only 9 weeks when you thought you were 10, your doctor will recommend waiting an additional week before drawing the NIPT blood sample.
The Optimal Window: Weeks 10-13
While NIPT can be performed any time from week 10 onwards, the optimal window is weeks 10-13. This timing offers several advantages that make it the sweet spot for most pregnancies:
- Fetal fraction is adequate but still rising: At 10-13 weeks, the average fetal fraction is 7-15% — well above the minimum threshold. Testing in this window minimises the risk of a no-call result due to low fetal fraction
- Results align with NT scan timing: The nuchal translucency (NT) scan is performed between 11 weeks 5 days and 13 weeks 6 days. By drawing NIPT blood at week 10-11, results arrive around the same time as (or shortly before) the NT scan, allowing your doctor to integrate both pieces of information simultaneously
- First-trimester decision window remains open: Having chromosomal information by 12-14 weeks leaves ample time for genetic counselling, confirmatory testing if needed (CVS at 11-14 weeks, amniocentesis from 15 weeks), and any decisions that families may need to make
- Early gender information: For families wanting to know the baby's gender, testing at 10-11 weeks means gender results arrive by 11-13 weeks — well before the mid-pregnancy ultrasound at 18-20 weeks
- Maximum time for repeat testing if needed: If the first sample returns a no-call result (1-5% of cases), there is still time to redraw at 12-13 weeks and receive results before the end of the first trimester
The ideal practical approach is to schedule your NIPT blood draw at week 10-11 of pregnancy. Allow 5-10 business days for results. This means you will receive results at approximately week 11-13, which is the same time frame as your NT scan. You and your doctor then have a comprehensive first-trimester screening picture — NIPT results, NT measurement, and any other first-trimester blood markers (PAPP-A, free beta-hCG) — all available together for interpretation and counselling.
Can NIPT Be Done After 13 Weeks? Testing in the Second Trimester
Yes. There is no upper gestational age limit for NIPT. The test can be performed at any point from week 10 through delivery. Fetal fraction actually increases throughout pregnancy — by the second trimester, it typically reaches 15-25%, making the test even more reliable from a fetal fraction perspective.
There are several reasons a woman might have NIPT later than the ideal 10-13 week window:
- Late booking: Some women do not present for prenatal care until the second trimester, especially if the pregnancy was unplanned or if they recently moved to Dubai
- Abnormal second-trimester screening: Women who did not have first-trimester screening may receive an abnormal result on the triple or quadruple marker test (weeks 15-20) and choose NIPT as the next step before deciding on amniocentesis
- Failed first-trimester NIPT: A no-call result at week 10-11, followed by another no-call at week 12-13, may prompt repeat testing at week 14-16 when fetal fraction is higher
- Abnormal ultrasound findings: An unexpected finding on the anatomy scan at 18-20 weeks may prompt NIPT if it was not done earlier
- Transfer of care: Women transferring prenatal care from another country may not have had NIPT offered at their previous provider
The main disadvantage of later testing is that results arrive at a point where the first-trimester screening window has closed. CVS is no longer an option after 14 weeks, and if amniocentesis is needed to confirm a high-risk result, the diagnosis may not be finalised until 17-20 weeks. This can add emotional stress and compress the timeline for decision-making. For this reason, earlier testing — within the 10-13 week window — is preferred whenever possible.
Schedule Your NIPT at the Right Time
Our prenatal care team at DCDC Dubai Healthcare City will coordinate your NIPT timing with your NT scan and first-trimester screening for a comprehensive assessment.
How NIPT Timing Relates to the NT Scan and First-Trimester Screening
The first trimester includes several screening assessments that work together to provide a comprehensive picture of your baby's health. Understanding how these assessments relate in timing helps you plan your appointments and maximise the information available to you and your doctor.
| Assessment | Timing | What It Measures | Results Turnaround |
|---|---|---|---|
| Dating ultrasound | Week 6-10 | Confirms viability, number of babies, gestational age | Immediate |
| NIPT blood draw | Week 10-13 (optimal 10-11) | Chromosomal screening (trisomies, sex chromosomes, gender) | 5-10 business days |
| NT scan | Week 11.5-13.5 | Nuchal translucency measurement, nasal bone, ductus venosus, tricuspid flow | Immediate |
| First-trimester blood markers | Week 9-13 | PAPP-A, free beta-hCG (for combined screening) | 3-5 business days |
| Combined screening result | Week 12-14 | Integrates NT, blood markers, and maternal age for trisomy risk | 1-2 weeks |
First-trimester screening timeline
The optimal coordination strategy is:
- Week 8-9: Dating ultrasound confirms gestational age and viability. Discuss NIPT with your doctor
- Week 10-11: NIPT blood draw. If combined screening is also planned, PAPP-A and free beta-hCG blood markers can be drawn at the same appointment
- Week 12-13: NT ultrasound scan. By this point, NIPT results may already be available, or will arrive within days. NT scan provides complementary information (structural assessment, NT measurement)
- Week 13-14: All first-trimester results are available for review. Your doctor integrates NIPT, NT scan, and blood marker results for a comprehensive risk assessment. If any result is concerning, genetic counselling and diagnostic testing (CVS or planning for amniocentesis at 15 weeks) are arranged
At DCDC Dubai Healthcare City, our prenatal care team coordinates all first-trimester screening assessments into an efficient timeline. We ensure that your NIPT, NT scan, and blood markers are timed to provide maximum information within the optimal window.
Results Turnaround: How Long to Wait
After your blood draw, the sample is sent to the NIPT laboratory for processing. The turnaround time depends on the specific laboratory platform:
- MaterniT21 (LabCorp): 5-7 business days — the fastest of the major platforms
- Harmony (Roche): 7-10 business days
- NIFTY (BGI): 7-10 business days
- Panorama (Natera): 7-14 business days — potentially longer due to more complex SNP analysis
These timeframes assume the sample is adequate and the fetal fraction is sufficient. If fetal fraction is below the threshold, the laboratory may attempt re-extraction from the same sample (adding 3-5 days) before reporting a no-call result. If a no-call occurs, a redraw is typically recommended in 1-2 weeks.
The waiting period can be emotionally challenging, particularly for women with anxiety about the results. Practical tips for managing the wait include: scheduling the blood draw and then planning a distracting activity for the following week, asking your clinic about electronic result delivery (many labs now send results digitally, which is faster than waiting for postal or fax delivery), and setting expectations — rather than checking every day, ask your clinic for the expected delivery date and check only then. At DCDC, we contact patients proactively as soon as results arrive, ensuring you do not have to wonder whether your results are in.
What Happens If You Test Too Early? Low Fetal Fraction Explained
If NIPT is performed before the fetal fraction has reached sufficient levels, the most likely outcome is a no-call result — also called an "uninformative" or "test failure" result. This means the laboratory was unable to extract and analyse enough fetal DNA from the sample to provide a reliable risk assessment. It is important to understand that a no-call result is NOT a positive result, NOT a negative result, and NOT an indication that something is wrong with the baby.
The no-call rate varies by platform and population but is typically 1-5% overall. However, in women who test very early (9-10 weeks) or who have high BMI, the no-call rate can be as high as 5-10%. The standard recommendation after a no-call result is to redraw in 1-2 weeks, as the fetal fraction increases by approximately 0.1% per day during the first trimester. Most women who receive a no-call result on the first attempt will receive a successful result on the second attempt.
There is one important clinical caveat: some chromosomal conditions, particularly trisomy 18 and trisomy 13, are associated with lower-than-expected fetal fraction. This means that a no-call result may be slightly more likely to occur in an affected pregnancy than in an unaffected one. Studies have shown that the risk of a chromosomal abnormality in pregnancies with low fetal fraction is approximately 2-4 times higher than in pregnancies with normal fetal fraction. For this reason, if a woman has two consecutive no-call results, her doctor should discuss the option of diagnostic testing (amniocentesis) rather than attempting a third NIPT blood draw.
To minimise the risk of low fetal fraction and maximise your chance of getting a result on the first attempt, follow these practical tips: wait until at least week 10 before testing (week 11 is even better for women with BMI > 30), ensure your gestational age has been confirmed by dating ultrasound (not just LMP calculation), and inform your doctor about your BMI so they can counsel you on the potential for low fetal fraction and recommend the optimal timing for your specific situation.
Time Your NIPT Perfectly
Let our prenatal care team at DCDC Dubai Healthcare City help you schedule NIPT at the optimal time for reliable results. Week 10-13 appointments available.
Coordinated with NT scan and first-trimester screening
Services associés au DCDC
Soins spécialisés et diagnostics avancés à Dubai Healthcare City
Questions frequentes
The Right Test at the Right Time
NIPT timing is straightforward: the earliest possible is week 10, the optimal window is weeks 10-13, and it can be done later if needed. The key to getting the most out of your NIPT is coordinating it with your overall first-trimester screening plan — dating ultrasound, NT scan, and blood markers — so that all results are available together for a comprehensive assessment.
For most women, the practical advice is simple: at your dating scan (week 8-9), confirm your gestational age and discuss NIPT with your doctor. Schedule the NIPT blood draw for week 10-11. Schedule the NT scan for week 12-13. By week 13-14, you will have a complete first-trimester screening picture — NIPT results, NT measurement, and blood markers — giving you and your doctor the information needed for confident, informed decision-making.
At DCDC Dubai Healthcare City, our NIPT service is fully integrated with our prenatal care programme. We coordinate the timing of your blood draw, NT scan, and other first-trimester assessments to ensure everything happens at the optimal time. Book your appointment today and let us take the guesswork out of your screening timeline.
Sources et references
Cet article a ete revise par notre equipe medicale et fait reference aux sources suivantes :
- American College of Obstetricians and Gynecologists — Cell-Free DNA Screening for Fetal Aneuploidy
- Fetal Medicine Foundation — First-Trimester Screening
- Ashoor et al. — Fetal Fraction in Maternal Plasma Cell-Free DNA at 11-13 Weeks (Fetal Diagnosis and Therapy)
- Society for Maternal-Fetal Medicine — NIPT Guidance Document
- International Society of Ultrasound in Obstetrics and Gynecology — NIPT Implementation Guidelines
Le contenu medical de ce site est revise par des medecins agrees DHA. Voir notre politique editoriale pour plus d'informations.
Redige par
Dr. Hadi Komshi
Specialist Internal Medicine
MD, Internal Medicine Specialist
Dr. Hadi Komshi is a Specialist in Internal Medicine with expertise in preventive health and comprehensive patient care. He practices at DCDC Dubai Healthcare City.
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