MENLO PARK, Calif., August 18, 2026
BillionToOne, Inc., a molecular diagnostics company developing quantitative genetic testing technologies, has announced publication of a large prospective study evaluating cell-free DNA (cfDNA) fetal risk assessment for recessive genetic conditions in a general-risk pregnancy population. Published in The Green Journal, the study evaluated 2,212 pregnant carriers across nine U.S. institutions, providing prospective evidence on the performance of cfDNA fetal risk assessment when used in routine prenatal screening. The study collected pregnancy outcomes for 98.6% of eligible pregnancies, strengthening the evidence base for evaluating this approach in real-world prenatal care.
Large Prospective Study Evaluates General-Risk Pregnancies
The study, titled A Prospective, Multi-Site Study of Performance of Cell-Free DNA Testing for Recessive Conditions in a Large, General-Risk Pregnancy Population, was designed to reflect the intended-use population for routine prenatal screening. Researchers evaluated pregnant individuals who were identified as carriers while partner carrier status was unknown at the time of testing. This approach differs from studies focused primarily on pregnancies involving known high-risk couples or other indications of elevated fetal genetic risk. The investigation assessed fetal risk for conditions including cystic fibrosis, spinal muscular atrophy, and alpha- and beta-hemoglobinopathies. According to the company, the prospective design and near-complete outcome ascertainment provide clinically relevant evidence for understanding how cfDNA fetal risk assessment may perform in general-risk pregnancies. Traditional carrier screening frequently relies on testing both biological parents to estimate the probability that a fetus will inherit a recessive condition. However, the company notes that partner testing may be incomplete, delayed or unavailable because of logistical, financial and access barriers. BillionToOne said its Unity Fetal Risk Screen is designed to assess fetal risk directly through cfDNA rather than relying solely on parental genotype information. In the study, the test demonstrated 94.4% sensitivity and 99.5% specificity, while the reported negative predictive value exceeded 99.9%.
cfDNA Testing Provides Quantitative Fetal Risk Assessment
A key finding highlighted by BillionToOne is the ability of the Unity Fetal Risk Screen to provide individualized estimates of fetal risk. The company reported that risk estimates can range from as high as 9 in 10 to as low as 1 in 10,000, providing a quantitative assessment beyond the maximum 1-in-4 risk traditionally associated with confirmed carrier status in both parents. The findings were also reported to be consistent across a racially and ethnically diverse study population, an important consideration for expanding access to prenatal genetic screening. The researchers emphasized that the study reflects the practical challenges encountered in routine prenatal care. When partner testing cannot be completed, conventional carrier screening may leave clinicians without a complete assessment of fetal risk. cfDNA fetal risk assessment may provide another approach by evaluating fetal genetic information directly, potentially helping identify pregnancies that could otherwise remain unidentified through incomplete partner screening. The findings also come as advances in treatment for inherited disorders increase the importance of earlier genetic diagnosis. Identifying pregnancies at increased risk can support appropriate follow-up and additional clinical evaluation, although the study itself evaluates screening performance rather than establishing treatment outcomes.
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Unity Portfolio Expands Prenatal Genetic Screening
The study supports BillionToOne’s broader Unity Complete® prenatal screening portfolio, which combines carrier screening, cfDNA-based fetal risk assessment and aneuploidy screening from a single maternal blood draw. The company’s technology is based on its Quantitative Counting Template™ (QCT™) approach and single-molecule next-generation sequencing platform, designed to quantify genetic targets at high resolution. BillionToOne said the publication follows its expansion of the fetal risk screening portfolio to include a 130-gene panel, reflecting continued development of comprehensive prenatal genetic testing. The prospective evidence from more than 2,200 pregnant carriers adds to the company’s efforts to establish cfDNA fetal risk assessment as a potential primary screening strategy for recessive conditions in general-risk pregnancies.
Source: BillionToOne press relese
