Persistent Uninterpretable or Failed Prenatal Cell-Free DNA Screening Indicates a High-Risk Pregnancy and is Associated With Biological Factors Interfering With cfDNA-Analysis: A Prospective Cohort Study

Abstract

Objective: To investigate maternal characteristics, underlying factors and perinatal outcome in pregnancies with persistent uninterpretable prenatal cfDNA screening in a general obstetric population (GOP). Methods: This study included pregnant individuals with persistent uninterpretable prenatal cfDNA screening results from December 2020 to December 2022. Prenatal cfDNA screening results were classified as uninterpretable due to low quality score (LQS) or low fetal fraction (LFF). Maternal autoimmune screening and a third prenatal cfDNA screening were performed later in pregnancy. Data on maternal characteristics and perinatal outcome were analyzed. Results: Among 123 pregnant individuals with failed prenatal cfDNA screening, 68% were due to LFF and 32% to LQS. Obesity and autoimmune diseases were significantly overrepresented. A third prenatal cfDNA screening at 24 weeks was informative in 77.1% cases, with a higher success-rate in the LFF group (87.8%). Maternal autoimmune screening revealed unknown triple positivity for antiphospholipid antibodies in 2.4%. Abnormal perinatal outcome was registered in 69.9% of patients, with higher rates of adverse perinatal outcome in the LFF group. Conclusion: Persistent uninterpretable prenatal cfDNA screening indicates a higher risk for adverse perinatal outcomes, especially in cases with LFF. Maternal autoimmune screening should be considered to identify high-risk pregnancies. A third prenatal cfDNA screening later in pregnancy can help stratify truly high-risk pregnancies and allows patients with initially uninterpretable results to make an informed decision about diagnostic testing.