The New Standard in Prenatal Care
First-and-only fetal antigen testing from cell-free DNA
Based on clinical evidence from Pregnancy (2025) & JAMA Network Open (2025)
Indirect proxy for fetal risk; do not reflect actual fetal antigen status
Incomplete; paternity uncertainty, zygosity ambiguity
Amniocentesis carries procedural risk; not ideal for surveillance
These methods persist not because they are ideal, but because no better option existed.
Titers escalated to critical thresholds regardless of fetal RBC antigen status — even when the fetus carried no risk of hemolytic disease.
Ashimi Balogun O, et al. Pregnancy 1.6 (2025): e70113.
Clinical Implication: Titer thresholds alone cannot distinguish true fetal risk from maternal immune response.
Clinically significant alloantibody identified
Available from 9 weeks gestation via UNITY Aneuploidy Screen
No further titers, no MCA Doppler. Routine prenatal care.
Focused surveillance: serial titers + MCA Doppler per protocol.
Determines fetal antigen status for up to 16 RBC antigens — covering 99% of antigens associated with HDFN.
*M and N must be selected at time of order; cannot be added post-submission.
Maternal IgG antibodies cross the placenta and bind to fetal RBCs bearing the target antigen, causing immune-mediated hemolysis.
| Mild | Neonatal jaundice |
| Moderate | Anemia requiring transfusion |
| Severe | Hydrops fetalis, stillbirth |
Risk is only present when the fetus inherits the target antigen from the father. Antigen-negative fetuses carry no risk of HDFN from maternal antibody.
Fetal/Neonatal Alloimmune Thrombocytopenia — maternal antibodies against fetal platelet antigens cause severe fetal thrombocytopenia.
The first-and-only non-invasive test to determine platelet fetal antigen status via cfDNA in the US. Designed for pregnancies at-risk or with a history of FNAIT.
Added to UNITY Aneuploidy™ Screen at any point during pregnancy
Uses the same cfDNA sample collected for aneuploidy screening
Add-on to existing UNITY Aneuploidy Screen order
Available exclusively through the UNITY Aneuploidy™ Screen platform. Contact: support@unityscreen.com · 650.460.2551
465 neonatal outcomes collected. 100% concordance for fetal RBC antigen genotyping via cfDNA.
Validation for RhD, C, c, E, K, Fyᵃ antigens. >99.9% sensitivity, specificity, and reproducibility.
Two guideline updates supporting the use of cfDNA to determine fetal RhD and fetal antigen status, citing UNITY clinical data as supporting evidence.
Clinical practice guideline recommends cfDNA for fetal antigen testing in alloimmunized pregnancies, citing UNITY data as primary evidence.
UNITY has contributed evidence to three clinical guideline updates and surpassed 1,000,000 tests ordered as of 2025.
| Parameter | Traditional Approach | UNITY cfDNA Testing |
|---|---|---|
| Fetal antigen determination | Indirect (partner testing, titers) | Direct from fetal cfDNA |
| Invasive procedure required | Sometimes (amniocentesis) | Never — maternal blood draw only |
| Gestational age at testing | Variable; often delayed | As early as 9 weeks |
| Surveillance for antigen-neg fetus | Continued (titers, MCA Doppler) | Discontinued per guideline |
| Sensitivity / Specificity | Variable; not standardized | >99.9% / >99.9% |
| Neonatal outcome concordance | Not directly measured | 100% (465 neonates) |
False positive and false negative results may occur. Results must be interpreted in the full clinical context by a qualified provider.
Laboratory-developed test (LDT) performed in a CLIA-certified, CAP-accredited laboratory. Not an FDA-approved test.
Test performance may vary based on fetal fraction, maternal age, zygosity, and other clinical factors.
M and N antigens must be selected at the time of ordering. They cannot be added after the test has been submitted.
| # | Citation | Key Finding |
|---|---|---|
| 1 | Ashimi Balogun O, et al. Pregnancy 1.6 (2025): e70113. | ~70% critical titers in antigen-negative fetuses |
| 2 | Moise KJ Jr, et al. JAMA Netw Open. 2025;8(11):e2544649. | CPG: cfDNA recommended; no surveillance if antigen-negative |
| 3 | Rego S, et al. Obstet Gynecol. July 2024. | 465 neonates; 100% concordance for RBC antigen genotyping |
| 4 | Alford B, et al. Sci Rep. 13.1 (2023): 12786. | >99.9% sensitivity, specificity; 100% concordance |
| 5 | BillionToOne. PR Newswire. December 2023. | Global collaboration with J&J Phase 3 trial (Nipocalimab/HDFN) |
| 6 | BillionToOne. Internal data on file. August 2025. | 1,000,000+ tests ordered |
Early cfDNA-based fetal antigen determination enables evidence-based de-escalation of surveillance when the fetus is antigen-negative.
The first non-invasive platelet antigen typing enables earlier risk stratification and management planning.
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UNITY Fetal Antigen NIPT is a screening test, not a diagnostic test. This is a laboratory-developed test (LDT) performed in a CLIA-certified, CAP-accredited laboratory. It is not an FDA-approved test. © 2026 BillionToOne, Inc. UN-FB-019-2601.