Affiliation:
1. Division of Maternal–Fetal Medicine, Department of Obstetrics and Gynecology, University of Washington, Seattle, Washington
2. School of Medicine, University of Washington, Seattle, Washington
3. Department of Obstetrics and Gynecology, University of Washington, Seattle, Washington
4. Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
Abstract
Objective Low fetal fraction (FF) on cell-free DNA (cfDNA)-based noninvasive prenatal screening (NIPS) is a common etiology for indeterminate results. As maternal Black race is implicated as a risk factor for low FF and more indeterminate results, we sought to evaluate this association.
Study Design This was a single-institution, retrospective cohort study of cfDNA-based NIPS performed between May 2017 and May 2022 with complete clinical data abstraction. We compared FF, indeterminate rates, and total cfDNA concentration among self-reported Black, White, and Other groups from NIPS results from 2017 to 2022 with full clinical data abstraction. Using linear regression and interaction testing, we evaluated associations between self-reported race, FF, indeterminate rate, and total cfDNA concentration.
Results In total, 1,591 participants met the inclusion criteria; 70.8% (n = 1,126) self-identified as White, 6.9% (n = 110) as Black, and 22.3% (n = 355) self-identified with another race. Mean FF was not different between the White, Black, or Other groups (11.8 vs. 11.2 vs. 11.7%, respectively, p = 0.52). This remained true after adjusting for body mass index (BMI), gestational age (GA) at draw, and fetal sex (all p > 0.17). Interaction testing for FF and total cfDNA by race with BMI, GA at draw, and fetal sex demonstrated no effect modification.
Conclusion In our population, maternal self-identified race, particularly Black race, does not affect FF. Biological plausibility for race-based differences on clinical tests requires ongoing thoughtful consideration.
Key Points