# First-Trimester Combined Screening vs. NIPT: Which to Choose

> Nuchal translucency plus bloodwork or a cell-free DNA blood draw — a board-certified OB-GYN breaks down the accuracy numbers, timing differences, insurance realities, and the one rule ACOG is firm about: pick one, not both.

*Published 2026-06-25 · By Priya Nair, MD*

The short answer
NIPT is the more accurate chromosomal screen — catching more than 99% of Down syndrome cases versus 79–96% for first-trimester combined screening — and can be done from nine weeks onward with a simple blood draw. Combined screening adds an NT ultrasound image that NIPT cannot provide. ACOG's firm rule: use one screen, never both together.

If you are eight or nine weeks pregnant and your provider hands you a decision about chromosomal screening, you are unlikely to feel ready for it. The terminology alone — nuchal translucency, cell-free DNA, PAPP-A, positive predictive value — can make what is really a practical, navigable choice feel like a graduate seminar. This guide cuts through that. We will compare what each test actually measures, how accurate each is, when and where you can get each one, what it costs, and how ACOG's current guidance should shape your decision.

*This article is general educational information, not medical advice. Talk to your provider or a board-certified genetic counselor about which screening option is right for your specific pregnancy.*

## What exactly does each test measure — and how does that affect accuracy?

**First-trimester combined screening (FTS)** pairs two things: an ultrasound measurement called the nuchal translucency (NT) and a blood draw that measures two maternal serum markers — pregnancy-associated plasma protein A (PAPP-A) and free or total beta-human chorionic gonadotropin (beta-hCG). These three data points are entered into a risk algorithm alongside your age to produce a composite probability estimate for trisomies 21 (Down syndrome), 18 (Edwards syndrome), and 13 (Patau syndrome). The test window is narrow: 11 to 14 weeks of gestation. [Cleveland Clinic explains](https://my.clevelandclinic.org/health/diagnostics/23333-nuchal-translucency) that outside that window — before 11 weeks or after 14 weeks — the NT measurement cannot be reliably interpreted.

**NIPT (non-invasive prenatal testing)**, also called cell-free DNA (cfDNA) screening, analyzes fragments of placental DNA that circulate in your bloodstream. Those fragments carry chromosomal information that sophisticated sequencing technology reads to calculate the probability that the fetus has extra or missing chromosomal material. The three major U.S. laboratory platforms — Natera's Panorama, Myriad Genetics' Prequel, and Labcorp's MaterniT21 PLUS — can each be performed from nine to ten weeks of gestation with results returning in roughly seven to fourteen days. No specialized ultrasound is required; the test is a blood draw alone.

The difference in accuracy is meaningful. NT ultrasound alone — without the serum markers — detects approximately 70% of trisomy 21 pregnancies. Adding PAPP-A and beta-hCG raises that figure to roughly 79–96% depending on the study and lab, at a false-positive rate of 3–5%. [A systematic review and meta-analysis of more than 200,000 pregnancies](https://pmc.ncbi.nlm.nih.gov/articles/PMC11098470/) found that NIPT achieves sensitivity exceeding 99% for trisomy 21 at a false-positive rate below 0.1%. For trisomies 18 and 13, NIPT similarly outperforms combined screening on both sensitivity and specificity.

  First-Trimester Combined Screening vs. NIPT: Key Comparison (2026)

      Feature
      First-Trimester Combined Screening
      NIPT (Cell-Free DNA)

      Earliest timing
      11 weeks (NT window closes at 14 weeks)
      9–10 weeks

      Trisomy 21 detection rate
      ~79–96% (with serum markers)
      >99%

      False-positive rate (T21)
      ~3–5%
      <0.1%

      NT ultrasound included
      Yes — provides fetal anatomy image
      No

      Detects cardiac/structural markers
      Yes (via elevated NT)
      No

      Requires certified NT sonographer
      Yes
      No

      Insurance coverage
      Broadly covered (routine standard care)
      Variable; expanding — Cigna and Aetna cover all ages

      Self-pay cost (without coverage)
      ~$449–$600
      ~$300–$1,500+

      Sex chromosome aneuploidies
      Not routinely detected
      Yes (monosomy X, XXY, XYY, XXX)

      Microdeletion screening
      No
      Optional add-on (lower PPV; confirmatory testing required)

## Is there anything combined screening catches that NIPT misses?

Yes — and it is clinically important. When the NT measurement is significantly elevated, typically above 3.5 mm, that finding is an independent marker not only for chromosomal aneuploidy but also for structural cardiac defects and certain single-gene syndromes. NIPT analyzes DNA and produces no anatomical image — it has no way to flag an enlarged NT space. According to [Johns Hopkins Medicine](https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/first-trimester-screening-nuchal-translucency-and-nipt), in pregnancies where the NT is unexpectedly elevated, providers typically proceed with a detailed fetal echocardiogram and genetic counseling regardless of what NIPT shows, because the ultrasound finding itself carries clinical weight beyond any blood-based screen.

This is the central reason why, even in an era when NIPT is statistically more accurate for common aneuploidies, the NT ultrasound has not been abandoned. In populations where a certified NT sonographer is accessible, combined screening provides useful additional anatomic information. In populations where that expertise is not nearby — rural communities, for example — NIPT's simpler, more accessible blood draw fills the gap.

There is one more practical consideration worth understanding: maternal body composition affects NIPT reliability in a way that combined screening does not. A nine-year analysis of 38,160 cases published in *Human Reproduction* found that mean fetal fraction — the proportion of placental DNA circulating in maternal blood — declined progressively with increasing maternal BMI, from 33.7% in underweight mothers to 22.2% in obese mothers. Higher BMI and lower fetal fraction were associated with significantly elevated false-positive rates for NIPT, particularly for monosomy X. Combined screening's serum markers are similarly influenced by maternal metabolic health, but in different ways. If you have questions about how your individual health factors may affect either test's reliability, that conversation belongs with your provider or a genetic counselor before you order the screen.

## What does ACOG say — and why does the 'pick one' rule matter?

[ACOG's January 2026 Practice Advisory on chromosomal screening](https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2026/01/screening-for-fetal-chromosomal-abnormalities) — which updated and superseded Practice Bulletin No. 226 (reaffirmed 2024) — is the current authoritative guidance for U.S. practice. Three things stand out:

  - **NIPT is now recommended for all pregnancies regardless of age or risk.** Prior guidelines restricted NIPT to high-risk patients (over 35, prior affected pregnancy, abnormal serum screen). That restriction is gone. ACOG now endorses offering cfDNA screening to any pregnant person who wants it.

  - **Use one screen, not both.** ACOG is explicit that combining first-trimester combined screening and NIPT produces discordant results and an unacceptably high cumulative false-positive rate. Both tests carry small independent error rates; layering them multiplies the probability that at least one flags a false positive, which can trigger unnecessary anxiety and invasive follow-up for a result that turns out to be normal.

  - **A positive screen from either test requires confirmatory diagnosis.** ACOG and ACMG both emphasize that patients have made irreversible pregnancy decisions based on positive NIPT results without first confirming the finding by CVS or amniocentesis — a documented clinical safety problem. Neither screen is a diagnosis. Confirmatory invasive testing remains the gold standard.

The November 2025 SMFM Consult Series No. 74 on cfDNA screening further updated guidance specifically on multifetal gestations, sex chromosome aneuploidies, microdeletions, and inconclusive (no-call) results — underscoring how actively this field is evolving. If you had NIPT guidance more than a year or two ago, it is worth asking your provider whether the recommendations have changed since.

Practical decision guide
Choose **combined screening** if: you are between 11 and 14 weeks, your center has a certified NT sonographer, you want an anatomic image of the fetal neck, and you are comfortable with a 3–5% false-positive rate for T21. Choose **NIPT** if: you want the most statistically accurate chromosomal screen available, you are earlier than 11 weeks or past the NT window, you want sex chromosome aneuploidy data, or a certified NT sonographer is not accessible. Either way: use only one approach, not both. If your NIPT comes back high-risk, confirmatory CVS or amniocentesis is the next step before any clinical decisions are made.

## What should I know about cost and insurance before scheduling?

First-trimester combined screening has long been considered routine standard prenatal care and is covered by most major commercial insurers and by Medicaid. Your out-of-pocket exposure is typically a standard copay plus, in some plans, a portion of the NT ultrasound bill. Total self-pay cost without insurance runs approximately $449–$600.

NIPT coverage is more variable. Cigna and Aetna now cover NIPT for all pregnant women without age restriction. Other payers still require documentation of a clinical indication — advanced maternal age, an abnormal serum screen, or a fetal structural anomaly — for coverage of average-risk pregnancies. Self-pay costs without coverage range from roughly $300 to over $1,500 depending on the laboratory and panel selected. All three major NIPT laboratories (Natera, Myriad Genetics, Labcorp) offer financial assistance programs that can reduce out-of-pocket costs to under $300 for qualifying patients — and all three provide access to free board-certified genetic counselors.

The practical step: before your provider orders NIPT, ask your insurer directly whether NIPT is covered for your age and risk profile, what documentation is needed, and what your maximum out-of-pocket exposure would be if the claim is denied. Getting that clarity before the blood draw — rather than after — protects you from bill surprises.

## Sources

1. [First Trimester Screening, Nuchal Translucency and NIPT](https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/first-trimester-screening-nuchal-translucency-and-nipt)
2. [The implementation and impact of non-invasive prenatal testing (NIPT) for Down's syndrome into antenatal screening programmes: A systematic review and meta-analysis](https://pmc.ncbi.nlm.nih.gov/articles/PMC11098470/)
3. [Nuchal Translucency Scan: Purpose, Procedure and Results](https://my.clevelandclinic.org/health/diagnostics/23333-nuchal-translucency)
4. [Practice Bulletin No. 226: Screening for Fetal Chromosomal Abnormalities](https://www.natera.com/wp-content/uploads/2021/04/ACOG-PB-226.pdf)
5. [Screening for Fetal Chromosomal Abnormalities — Practice Advisory](https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2026/01/screening-for-fetal-chromosomal-abnormalities)
6. [First-Trimester Screening vs. NIPT: Which Test Gives You More Accuracy?](https://mynucleus.com/blog/first-trimester-screening-vs-nipt)
7. [The impact of maternal age, BMI, and fetal fraction on false-positive rates in prenatal aneuploidy testing: a nine-year analysis of 38,160 cases](https://academic.oup.com/humrep/article/40/Supplement_1/deaf097.861/8170641)

---
Source: https://natalnew.com/prenatal-care/first-trimester-screening-vs-nipt
Index: https://natalnew.com/llms.txt · Full text: https://natalnew.com/llms-full.txt