How it works
During pregnancy, small fragments of the placenta's DNA circulate in your bloodstream. NIPT — non-invasive prenatal testing, also sold as cell-free DNA screening — sequences those fragments from a single blood draw and counts whether there is more chromosomal material than expected. It can be done from around ten weeks and needs no needle near the uterus, so it carries no miscarriage risk.
What it screens for
- Trisomy 21 (Down syndrome) — detection above 99 percent.
- Trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome).
- Sex chromosome conditions such as Turner and Klinefelter syndrome, with lower accuracy.
- Some microdeletions, in expanded panels — these have notably lower accuracy and more false positives.
- Rhesus D status and fetal sex, though in India disclosure of fetal sex is illegal under the PCPNDT Act and laboratories will not report it.
NIPT does not screen for neural tube defects, structural heart defects, cleft lip or most single-gene conditions. You still need the 11 to 13 week scan and the 18 to 22 week anomaly scan.
Screening versus diagnosis
This is the point most often misunderstood. A "high risk" NIPT result is a probability, not a finding. The chance that a high-risk result is genuine — the positive predictive value — depends on how common the condition is and on your age. For trisomy 21 in an older mother it may exceed 90 percent; for a rare microdeletion in a young mother it can be under 20 percent. Every high-risk result therefore needs confirmation by amniocentesis or chorionic villus sampling, which test the baby's own cells and are diagnostic.
A low-risk result is reassuring but not a guarantee, and it says nothing about conditions the test does not cover.
Practical details in India
NIPT typically costs between ₹12,000 and ₹25,000 depending on the panel, and is usually not covered by insurance. Results take seven to fourteen days. Around 1 to 5 percent of samples fail to give a result, more often at higher BMI or if taken too early; a repeat draw usually resolves it. Twin pregnancies, a vanishing twin, IVF with a donor egg, and maternal blood transfusion all affect interpretation, so tell the laboratory.
Who should consider it
NIPT is offered to all pregnancies in many countries, and is particularly worth discussing if you are over 35, have an abnormal first-trimester combined screen or nuchal translucency, have had a previous affected pregnancy, or simply want the most accurate screening available without procedure risk. It is also a reasonable step before deciding on amniocentesis, since a low-risk NIPT often removes the need for an invasive test.
Before you book
Ask which conditions the panel covers, what the failure rate and turnaround are, and — most importantly — what happens next if the result is high risk. Ideally arrange genetic counselling as part of the package, so the result arrives with someone qualified to explain it.