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: · NIPS is widely used to screen for fetal aneuploidy.. · FF is an important test metric, and low FF is associated with adverse outcomes, like aneuploidy.. · In existing studies, Black race is implicated as a risk factor for lower FF.. · Our study found no differences in FF between groups by self-reported race.. · Biological plausibility for race-based differences on clinical tests requires ongoing consideration..
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