The first time I heard about NIPT, I was at a baby shower. A friend of a friend — let's call her "Maya" — was describing her experience. She'd gotten a "high risk" result for trisomy 18. The test said her baby had an 85% chance of having a severe chromosomal condition. She spent three weeks spiraling — researching, crying, preparing for the worst. She started picking out burial plots.
Then she had an amniocentesis. The amnio showed that the baby was completely normal. The NIPT had been a false positive.
Maya told the story with tears in her eyes. "I lost three weeks of my pregnancy to terror. Three weeks I'll never get back."
I remember thinking: why didn't anyone explain the test properly?
Years later, I had my own NIPT experience. With my first pregnancy, I was 32. My doctor offered it. I said yes without really understanding. The results came back low risk. I felt relieved and moved on. No harm done.
With my second pregnancy, I was 35. I took the test again. This time, the results came back "no result" for one of the chromosomes. The lab said "insufficient fetal DNA." I spent a week in a panic. What did that mean? Was something wrong? I called my midwife. She said, "It happens. Redraw the blood." The second draw came back low risk. Another false alarm.
With my third pregnancy (current), I almost didn't take it. The anxiety from the second experience was still fresh. But I did — and I met with a genetic counselor first. That meeting made all the difference.
Here's what I learned.
NIPT is a screening test, not a diagnostic test. It looks for fragments of fetal DNA in your blood and calculates a probability. It is very good at ruling OUT conditions (high negative predictive value). If it says low risk, you can be confident. But it is not perfect at ruling IN conditions. The positive predictive value (the chance that a high-risk result is actually correct) depends on your age and the condition's rarity.
For a 25-year-old, the PPV for trisomy 21 is about 80-85%. That means a high-risk result has a 15-20% chance of being wrong. For trisomy 18, the PPV is lower — maybe 50-70%. For trisomy 13, even lower. For rare conditions, the false positive rate can be as high as 80-90% in young women. Yes, 80-90%.
Yet most providers don't explain this. They offer the test. You sign the form. You get the result. And if it's high risk, you're left alone with Google and your terror.
The correct next step after a high-risk NIPT is diagnostic testing: chorionic villus sampling (CVS) at 10-13 weeks or amniocentesis at 15-20 weeks. CVS and amnio carry a small risk of miscarriage (about 1 in 500 to 1 in 1,000). That risk is lower than the chance of a false positive for many conditions, but it's not zero. You need to understand both the risk of the test and the risk of not knowing.
I had another patient — "Naomi" — who got a high-risk result for a microdeletion on NIPT. She was 28. The condition was so rare that the PPV was estimated at 5-10%. Her genetic counselor told her that 90-95% of women with her result would have a normal baby. But Naomi couldn't accept the uncertainty. She had an amnio. The baby was normal. She was relieved but also angry. "Why did I take that test?" she said. "It gave me nothing but anxiety."
On the other hand, I had a patient — "Elena" — who got a low-risk NIPT but had a concerning finding on her anatomy scan. The amnio confirmed a rare microdeletion that NIPT doesn't screen for. Elena said, "I thought NIPT cleared me. I didn't know there were other things."
That's the other limitation of NIPT: it screens for a handful of conditions. There are thousands of possible genetic anomalies. A low-risk NIPT is not a clean bill of health.
So what's my advice?
Before you take NIPT, meet with a genetic counselor. Ask about the PPV for your age and the conditions screened. Ask what the test cannot detect. Ask what you would do with a high-risk result. If you wouldn't do CVS or amnio, then NIPT may not be useful — the information would just cause anxiety without changing management.
If you decide to take the test, prepare yourself mentally. A "no result" is not a bad result. A "high risk" is not a diagnosis. Wait for the diagnostic testing before you panic.
I took NIPT with my first and third pregnancies. I skipped it with my second after the false alarm. There's no right answer for everyone. There's only the right answer for you. Just make sure you understand the test before you take it. Knowledge is power — but incomplete knowledge is anxiety. Get the complete picture.
This article reflects evidence and clinical experience. Always discuss prenatal screening with your provider and a genetic counselor.
— Emily Carter, IBCLC