Prenatal Genetic Screening: NIPT, Nuchal Translucency, and the Quad Screen
Prenatal genetic screening estimates the chance that a pregnancy is affected by certain chromosomal conditions, most commonly Down syndrome (trisomy 21). These are screening tests, not diagnostic ones — they give you a probability, not a yes-or-no answer — and every one of them is optional. Understanding what each test actually measures makes it easier to decide which, if any, are right for you.
Last updated August 2026
Cell-free DNA screening (NIPT)
A blood draw from the pregnant person, usually done at 10 weeks or later, that analyzes small fragments of placental DNA circulating in the blood. It's the most accurate of the screening options for the most common chromosomal conditions (trisomies 21, 18, and 13) and can also reveal fetal sex. It's a screening test, not diagnostic — a high-risk result still needs to be confirmed with a diagnostic test before any decisions are made based on it.
First-trimester screening (nuchal translucency + blood work)
Done between 11-14 weeks, combining an ultrasound measurement of fluid at the back of the baby's neck (nuchal translucency) with a blood test, to estimate risk for the same trisomies. It's less accurate than NIPT for chromosomal risk specifically, but the ultrasound portion also checks early fetal anatomy and can flag findings unrelated to chromosomes, which is a real advantage some people specifically choose it for.
Quad screen (second trimester)
A blood test done between 15-20 weeks measuring four substances, used either as a stand-alone second-trimester option or combined with first-trimester results for a more accurate combined estimate. It's the option typically used for anyone who missed first-trimester screening but still wants a blood-based risk estimate.
If a screening result comes back higher-risk
A higher-risk screening result is not a diagnosis — it means further information is worth getting, not that something is confirmed to be wrong. Diagnostic options (chorionic villus sampling or amniocentesis, which sample placental or amniotic fluid genetic material directly) give a definitive answer and are typically offered as the next step, along with genetic counseling to walk through what the numbers actually mean for your specific situation.
These are all optional
None of this screening is required, and declining it doesn't affect the rest of your prenatal care. Some people want as much information as early as possible; others prefer not to test unless there's a specific reason to. Both are reasonable choices, and it's worth deciding before the testing window rather than in the middle of it.
Worth discussing with your provider
Educational information only — general patterns that vary by person. This is not medical advice, a diagnosis, or a substitute for care from your own clinician.
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