Prenatal Screening · DNA
NIPT — Non-Invasive Prenatal Test
Blood test from 10 weeks pregnant that screens for Down syndrome (T21), Edwards (T18), Patau (T13), sex chromosomes. >99% accurate for T21. NHS free if first-trimester risk ≥1 in 150; otherwise £200-600 privately.
Last reviewed 2 June 2026
cfDNA / NIPT — result interpretation
What does my NIPT result mean?
Condition
1 in
Typical priors: maternal age 30 ~1:1000 T21; age 35 ~1:380; age 40 ~1:130.
NIPT result
Enter your prior risk to see PPV / NPV for this result.
Educational tool — NIPT is a SCREEN, not diagnostic. A positive NIPT should be confirmed by CVS or amniocentesis before any decisions. ACOG 2020 endorses NIPT for ALL pregnancies regardless of age or risk. Fetal fraction ≥ 4 % is required for a valid result; low FF (commonly in maternal obesity, early gestation) requires resampling.
What does this mean?
NIPT works by sequencing fragments of fetal DNA (actually placental cell-free DNA) that circulate in maternal blood from about 10 weeks onward. For trisomy 21 sensitivity is > 99 % and specificity ~99.9 % — far better than serum + NT screening. Positive predictive value (PPV) depends on prior probability: in a 25-year-old with a 1:1,250 background risk, a positive T21 NIPT has PPV ~50–60 %; in a 40-year-old with 1:60 risk, PPV rises to ~90 %. That’s why NIPT is a SCREEN — every positive result should be confirmed by CVS or amniocentesis before irreversible decisions. NIPT also reports sex chromosomes (X/Y) reliably and increasingly screens for microdeletions (22q11.2 / DiGeorge), but PPV for microdeletions is low (~5– 20 %). A “no-call” result usually means low fetal fraction — repeat the test in 1–2 weeks.
What is NIPT?
NIPT (Non-Invasive Prenatal Testing), also called cfDNA screening, is a blood test from 10 weeks pregnant that screens for chromosomal conditions in your baby.
~10% of the DNA in your blood during pregnancy comes from the placenta (baby’s DNA). Lab analyses for:
- Trisomy 21 (Down syndrome).
- Trisomy 18 (Edwards).
- Trisomy 13 (Patau).
- Sex chromosomes (Turner XO, Klinefelter XXY).
- Some labs: microdeletions (DiGeorge, Cri-du-chat).
When can I have NIPT?
- From 10 weeks gestation.
- NHS: from 11+0 weeks (with first-trimester scan).
- Privately: 10+ weeks.
- Results in 5-10 working days (private: 3-5 days possible).
How accurate is it?
- T21 (Down): >99% sensitivity, <0.1% false-positive.
- T18 / T13: ~95-99% sensitivity, higher false-positive.
- Sex chromosomes: ~95% accurate.
- Microdeletions: less accurate.
It’s a screen, not a diagnosis. Positive result needs confirmation with CVS or amniocentesis.
Is NIPT free on the NHS?
Free if first-trimester screening showed risk ≥1 in 150.
Normal risk: NHS doesn’t routinely offer; can pay privately (£200-600).
Private providers: Harmony, Panorama, NIFTY, IONA. Check what’s included — some packages cover sex chromosomes + microdeletions, others basic only.
NIPT vs nuchal scan
Different roles — most parents have BOTH.
- Nuchal scan: ultrasound 11-14 weeks; dating, viability, early anomaly, neck fluid + biochemistry combined screening.
- NIPT: blood test, just chromosomal screening, highest accuracy.
Neither replaces the 20-week anomaly scan.
Can NIPT tell baby’s sex?
Yes — 95-99% accurate from 10 weeks. Detects Y chromosome material in mum’s blood:
- Y detected = MALE (XY).
- No Y = FEMALE (XX).
Some parents request sex NOT disclosed if they want to wait for ultrasound surprise.
What if my result is “high risk”?
Doesn’t mean baby definitely has the condition.Positive Predictive Value (PPV) for T21 in low-risk population: ~80-90% (varies by age).
Next steps:
- Genetic counselling.
- Diagnostic test — CVS (~11-13 wk) or amniocentesis (15+ wk) for definitive answer.
~5-10% of NIPT positives turn out negative on confirmation. Take time. Support: ARC (Antenatal Results & Choices) UK; SOFT for T18 / T13.
What if result is “no call”?
Happens in 1-5%. Causes:
- Low fetal fraction (<4% baby DNA — common in higher BMI, very early pregnancy, twins).
- Technical issues.
- Rarely indicates underlying chromosomal abnormality.
Options: redraw blood in 1-2 weeks (often successful); proceed with FTCS or quad screen; diagnostic test if concerned.
Different scenarios — using NIPT
Scenario 1: First pregnancy, age 32, low-risk so far
Optional — not NHS-funded routinely. Private if you want extra accuracy / reassurance. Cost £200-600.
Scenario 2: Age 38, FTCS just showed 1 in 80 risk
NHS-funded NIPT recommended. Likely highly informative. If positive, plan CVS / amnio. If negative, very reassuring.
Scenario 3: After IVF
Recommended even if PGT-A normal — verifies actual pregnancy chromosomes.
Scenario 4: Identical twins, want screening
Possible but check provider supports twins. Some labs decline. NHS not standard. Discuss accuracy limitations.
Scenario 5: NIPT positive for T21, what next
Genetic counselling. CVS or amniocentesis for confirmation. Time to think. ARC for support. Information about Down syndrome from DSA (Down’s Syndrome Association UK).
Care guidance — using NIPT well
- 10+ weeks for accurate results.
- Combined with nuchal scan for full screening.
- Doesn’t replace 20-week anomaly scan.
- Choose your package — basic vs sex chromosomes vs microdeletions.
- Decide gender disclosure ahead of time.
- Positive result: confirm with CVS / amnio.
- Negative result: very reassuring but not 100%.
- Genetic counselling for any positive / uncertain result.
- ARC charity for support: arc-uk.org.
- Don’t over-interpret — NIPT doesn’t test most conditions.
Sources
- NHS Fetal Anomaly Screening Programme (FASP). NIPT in the NHS.
- RCOG / BMFMS / ARC. Joint position paper on NIPT 2019.
- ACOG Practice Bulletin 226. Screening for fetal chromosomal abnormalities.
- Gil MM, et al. Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: meta-analysis. UOG 2017.
- Antenatal Results & Choices (ARC). arc-uk.org.
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Frequently asked questions
What is NIPT and what does it test for?
NIPT (Non-Invasive Prenatal Testing), also called cfDNA screening, is a BLOOD TEST done from 10 weeks pregnancy that screens for chromosomal conditions in your baby. ~10% of the DNA in your blood during pregnancy comes from the placenta (baby's DNA). Lab analyses this for: TRISOMY 21 (Down syndrome — extra chromosome 21), TRISOMY 18 (Edwards — usually fatal in 1st year), TRISOMY 13 (Patau — usually fatal in 1st year), and SEX CHROMOSOMES (Turner XO, Klinefelter XXY, etc.). Some labs also screen microdeletions (DiGeorge, Cri-du-chat). Very accurate for T21 (>99% sensitivity); slightly less for rarer conditions.
When can I have NIPT?
FROM 10 WEEKS gestation (some labs say 9-10 weeks). Before this, not enough fetal DNA in your blood for reliable results. NHS NIPT (UK): available from 11+0 weeks (because integrated with first-trimester scan). PRIVATELY: usually 10+ weeks. CAN BE TAKEN any time after that — through to delivery, though most do early (10-16 weeks) to inform decisions early. Results take 5-10 working days usually. PRIVATE NIPT: faster turnaround possible (3-5 days).
How accurate is NIPT?
VERY ACCURATE for COMMON trisomies — but it's a SCREEN, not a diagnosis. T21 (Down): >99% sensitivity, >99% specificity. FALSE POSITIVE rate <0.1% for T21. T18 / T13: slightly less accurate (~95-99% sensitivity, higher false-positive). SEX CHROMOSOMES: ~95% accurate. MICRODELETIONS (DiGeorge etc): less accurate, more false positives. POSITIVE RESULT ≠ definite — confirm with diagnostic test (CVS or amniocentesis). NEGATIVE RESULT very reassuring (~99.5% chance baby unaffected for T21). DOES NOT detect ALL conditions — just specific chromosomal ones tested.
Is NIPT free on the NHS?
NHS NIPT EXPANSION (rolled out 2021-2022): NIPT available FREE if first-trimester screening (FTCS) showed RISK ≥1 in 150. NORMAL RISK (<1 in 150): NHS doesn't routinely offer; can pay privately. PRIVATE NIPT in UK: £200-600 depending on provider (Harmony, Panorama, NIFTY, etc.) and what's included. SOME private GPs / clinics include sex chromosomes + microdeletions; basic test cheaper. SCOTLAND / WALES / NI may have slightly different access criteria. US: insurance-dependent; can be $250-2000+.
Do I need NIPT instead of nuchal scan?
DIFFERENT roles. NUCHAL TRANSLUCENCY SCAN (NT, part of first-trimester screen 11-14 weeks): ultrasound measure of fluid at back of baby's neck PLUS dating + viability + early anomaly screen. DOES MORE than just chromosomal screening. NIPT: just chromosomal screening, BLOOD test. MOST RECOMMENDED: HAVE BOTH — nuchal scan gives anatomy info, NIPT gives best chromosomal screening accuracy. Doesn't replace 20-week anomaly scan.
Can NIPT tell baby's sex?
YES — usually accurate from 10 WEEKS. Detects Y chromosome material in maternal blood. If Y detected = MALE (XY). If no Y = FEMALE (XX). Accuracy: 95-99% from 10 weeks. SOME parents request gender NOT disclosed with NIPT result if they want to wait for ultrasound. Can also detect SEX-CHROMOSOME aneuploidies: 45,X (Turner), 47,XXY (Klinefelter), 47,XXX, 47,XYY.
What if my NIPT result is 'high risk' / positive?
DOESN'T MEAN BABY DEFINITELY HAS THE CONDITION. POSITIVE PREDICTIVE VALUE (PPV) for T21 in low-risk population: ~80-90%. NEXT STEPS: (1) GENETIC COUNSELLING; (2) CONFIRMATORY DIAGNOSTIC TEST — CVS (chorionic villus sampling, ~11-13 weeks) or AMNIOCENTESIS (15+ weeks). These give DEFINITIVE answer. ~5-10% of NIPT 'positives' turn out NEGATIVE on confirmation (false positives, placental mosaicism). TAKE TIME — these decisions are big. SUPPORT: Antenatal Results & Choices (ARC) UK charity; SOFT for T18/T13 support; Down's Syndrome Association.
What if NIPT result is 'no call' / inconclusive?
Happens in 1-5% of tests. CAUSES: (1) LOW FETAL FRACTION (<4% DNA from baby) — common in high BMI, very early pregnancy, twins; (2) TECHNICAL ISSUES; (3) RARELY indicates underlying chromosomal abnormality. OPTIONS: (1) REDRAW BLOOD in 1-2 weeks (often successful second time as fetal fraction rises); (2) PROCEED with first-trimester combined screen or quad screen; (3) DIAGNOSTIC test if concerned. RECURRENT 'no call': slight increase in chromosomal abnormality risk — discuss with genetic counsellor.
Should I have NIPT if I'm low-risk?
PERSONAL CHOICE. ARGUMENTS FOR: more accurate than first-trimester screen alone; non-invasive (no miscarriage risk); reassuring for many. ARGUMENTS AGAINST: privately ~£200-600; results still need confirmation if positive; screens for conditions you may not want to know about (some sex chromosome conditions are mild and adults often unaware until later). NHS-FUNDED in UK only if FTCS shows ≥1 in 150 risk. SOME parents prefer NOT to screen — that's valid too. INFORMED CHOICE essential — book genetic counselling if uncertain.
What if I'm carrying twins?
NIPT CAN be done in twins but: (1) LOWER FETAL FRACTION typically; (2) MAY NOT distinguish which twin if discordant; (3) SOME LABS only do dichorionic (separate placentas) twins; (4) ACCURACY lower than singleton. NHS: NIPT in twins not standard offer; private possible depending on provider. NIFTY and Harmony can test twins; check provider. POSITIVE RESULT: harder to interpret — may need both babies tested invasively. VANISHING TWIN: NIPT may be unreliable if vanishing twin recent (fetal DNA from miscarried twin persists).
Are there things NIPT doesn't test for?
YES — many. NIPT tests specific CHROMOSOMAL conditions. DOES NOT TEST FOR: (1) STRUCTURAL anomalies (heart defects, spina bifida, cleft palate — these need ultrasound); (2) SINGLE-GENE conditions (cystic fibrosis, sickle cell, Tay-Sachs — need separate carrier screening); (3) RARE chromosomal microdeletions beyond panel; (4) NEW MUTATIONS during development; (5) LEARNING DIFFICULTIES, autism, ADHD; (6) PERSONALITY, traits. NIPT is ONE PIECE of antenatal care, not comprehensive.
Is NIPT safe?
YES — completely safe. It's a BLOOD TEST from mum's arm — no risk to baby. UNLIKE CVS or amniocentesis (invasive, small miscarriage risk ~0.1-0.5%), NIPT carries NO miscarriage risk. NO IMPACT on baby's development. SOME WOMEN feel anxious waiting for results — that's normal. AVOID testing too early (<10 weeks) — wasted money + emotional rollercoaster if no result. EAT/DRINK normally before test. STANDARD blood draw, ~10 ml.
Will my insurance / NHS cover NIPT?
UK NHS: yes if FTCS risk ≥1 in 150. NOT routinely covered for low-risk. PRIVATE: £200-600 self-pay. SOME private maternity packages include. US: Aetna, Cigna, BCBS often cover for women aged ≥35 OR with positive FTCS — varies by plan; without coverage $250-2000. AUSTRALIA: not yet Medicare-funded routinely, private ~A$400-700. CHECK with provider what's included.
Should I have NIPT after IVF?
YES — many IVF couples have NIPT regardless of age risk. WHY: extra information after long fertility journey; reassurance valuable. EVEN AFTER PGT-A (Pre-implantation Genetic Testing of Aneuploidy) on the embryo, NIPT still recommended — PGT-A misses some mosaicism and only tests embryo cells. NIPT VERIFIES the chromosomal status of actual pregnancy. ALSO useful: confirms sex of baby (private NIPT) if PGT-A done for medical reasons hasn't disclosed sex.
What about NIPT after a positive first-trimester screen?
STRONGLY RECOMMENDED. If FTCS shows ≥1 in 150 risk, NIPT is the next step. WHY: more accurate than FTCS alone; non-invasive; reduces need for invasive testing. NHS-FUNDED in this scenario. PATHWAY: FTCS → high risk → NIPT → if positive → CVS or amnio for definitive diagnosis. Reduces unnecessary invasive procedures by ~80%. IF NIPT POSITIVE → very high chance condition present (PPV 80-95% for T21) → confirmation testing.
How does this relate to other calculators on BumpBites?
Companion: /calculators/first-trimester-screen for nuchal scan + biochemistry; /calculators/quad-screen for second-trimester serum screen; /calculators/pregnancy-test-timing; /calculators/implantation; /calculators/conception-date; /calculators/due-date; /calculators/twin-probability for twins context; /calculators/pregnancy-week for gestation timing.