Quick answer: NIPT — non-invasive antenatal testing — has transformed antenatal screening over the past decade.
NIPT — non-invasive antenatal testing — has transformed antenatal screening over the past decade. A simple blood draw from the mother can screen for chromosomal conditions with remarkable accuracy, providing many parents with significant peace of mind and, when needed, important early information.
What NIPT Screens For
NIPT analyzes cell-free fetal DNA (cfDNA) — placental DNA fragments that circulate in the mother’s bloodstream. It primarily screens for: Trisomy 21 (Down syndrome) — extra chromosome 21; the most common chromosomal condition. Trisomy 18 (Edwards syndrome) — extra chromosome 18; typically incompatible with long-term survival. Trisomy 13 (Patau syndrome) — extra chromosome 13; also typically severe. Sex chromosome abnormalities including Turner syndrome (45,X) and Klinefelter syndrome (47,XXY). Fetal sex — accuracy above 99%. Expanded panels also screen for microdeletions associated with DiGeorge syndrome, Angelman syndrome, and others.
Sensitivity and Specificity: What the Numbers Mean
For Down syndrome, NIPT has approximately 99% sensitivity (correctly identifies 99% of affected pregnancies) and 99.7% specificity (correctly identifies 99.7% of unaffected pregnancies). This sounds near-perfect — but positive predictive value depends on pre-test probability. At age 25 with no family history, Down syndrome risk is roughly 1 in 1,250. Even a highly specific test generates a meaningful false positive rate in a low-risk population. A positive NIPT is not a diagnosis — it is a risk assessment requiring diagnostic confirmation (CVS or amniocentesis) before any decision is made.
A Positive Result: What Happens Next
A positive NIPT should always be followed by: Genetic counseling — a genetic counselor explains the result, the false positive rate in your specific context, and your options. This appointment is essential and should not be skipped. Confirmatory diagnostic testing — CVS at 10–13 weeks or amniocentesis at 15–20 weeks both provide definitive diagnoses with >99.9% accuracy, each carrying approximately 0.5–1% procedure-related miscarriage risk. Support resources — organizations like the National Down Syndrome Society offer support for families navigating any outcome.
Cost and Access
In the US, insurance coverage for NIPT is generally available for women 35 and older, those with prior chromosomal pregnancies, or those with abnormal ultrasound findings. For lower-risk women under 35, coverage varies. Self-pay ranges from $200–$800; most labs offer financial assistance programs. In the UK, NIPT is available on the NHS for women with high-risk first trimester screening results.
Frequently Asked Questions
Is NIPT the same as amniocentesis?
No — NIPT is a screening test (estimates risk), not a diagnostic test (provides a definitive answer). Amniocentesis and CVS are diagnostic — they directly analyze fetal chromosomes. NIPT has no fetal risk (blood draw from mother only). Amniocentesis has a small procedural miscarriage risk. NIPT cannot detect all chromosomal conditions; diagnostic tests can.
Can NIPT results be wrong?
Yes — false positives and false negatives do occur. Confined placental mosaicism (where the placenta has a chromosomal abnormality the baby doesn’t) can cause false positives. Maternal cancers can elevate cfDNA signals. Failed NIPT (insufficient fetal fraction, occurring in 1–5% of tests) is more common at early gestations and higher BMIs — failed tests should be repeated or followed by alternative screening.
Should I get NIPT if I’m under 35?
NIPT is appropriate for any pregnant woman wanting comprehensive chromosomal screening regardless of age. While risk increases with age, chromosomal conditions occur at all ages — and because more babies are born to women under 35, the majority of Down syndrome pregnancies statistically occur in younger women. The decision should be guided by your values and what information would be meaningful to you.
Related Reading
- 10 weeks pregnant: nuchal translucency scan explained
- Gagging vs choking in babies: how to tell the difference
Found this helpful? Sign up to the LylyMama newsletter for evidence-based guides, honest essays and practical advice delivered to your inbox every week.
