Obstetrical, Perinatal, and Genetic Outcomes Associated With Nonreportable Prenatal Cell-Free DNA Screening Results
Authors: Norton Mary E. , MacPherson Cora , Demko Zachary , Egbert Melissa , Malone Fergal , Wapner Ronald J. , Roman Ashley S. , Khalil Asma , Faro Revital , Madankumar Rajeevi , Strong Noel , Haeri Sina , Silver Robert , Vohra Nidhi , Hyett Jon , Martin Kimberly , Rabinowitz Matthew , Jacobsson Bo , Dar Pe'er 
Published: March 2024

Although cell-free DNA (cfDNA) prenatal screening is widely used and has high sensitivity and specificity, there are circumstances in which the screening does not provide an interpretable result. Although this is relatively uncommon, it happens enough that clinical implications and potential reasons for follow-up should be studied and assessed. This study was designed to evaluate outcomes for pregnancies with nonreportable results on cfDNA screening tests.

This study was a secondary analysis of the data from a multicenter prospective observational study of cfDNA screening for aneuploidy and 22q11.2 deletion syndrome. All patients were tested for trisomies 13, 18, and 21, as well as the 22q11.2 deletion syndrome, and all patients had confirmatory testing on the newborns in addition to collecting obstetric and perinatal outcomes. Inclusion criteria were women older than 18 years and at greater than 9 weeks of gestation with a singleton pregnancy. Exclusion criteria were having received cfDNA screening results before enrollment, organ transplant, ovum donation, vanishing twin, or being unwilling to provide a newborn sample. The primary outcome was the rate of adverse obstetrical and perinatal outcomes, including aneuploidy; preterm birth at less than 28, 34, or 37 weeks' gestation; preeclampsia; small for gestational age birth; and a composite outcome that included preterm birth before 37 weeks, preeclampsia, stillbirth at greater than 20 weeks, and small for gestational age.

Final analyses included 17,851 individuals who had cfDNA screening, confirmatory genetic testing on the newborn, and obstetrical and perinatal outcomes recorded. Nonreportable results were found in 602 individuals (3.4%) after the first draw, with 32.2% of these due to low fetal fraction. Another third of the cohort had patterns where the risk of aneuploidy was uninterpretable but with an adequate fetal fraction, and in the final third, the fetal fraction could not be measured. Of the original 602 cases of nonreportable findings, 427 had a second draw, with 112 of these (26.2%) again having nonreportable results. There were no significant differences in baseline characteristics of age and parity for those with successful versus nonreportable test results; gestational age was significantly higher in individuals with nonreportable results (14.4 vs 13.4 weeks, P < 0.001), as was body mass index (26.2 vs 31.3), and the rate of chronic hypertension (4.0% vs 9.7%).

In this cohort, there were 133 genetically confirmed trisomies, with 100 fetuses with trisomy 21, 18 individuals with trisomy 18, and 15 individuals with trisomy 13. Overall, the rate of aneuploidy was 1.7% in individuals with nonreportable results, versus 0.7% in those with reported results (P = 0.013; adjusted odds ratio [aOR] 2.1; 95% confidence interval [CI], 1.1–4.0). Rates of preterm birth were also higher in those with nonreportable test results, with delivery at less than 34 weeks at 1.5% in those with a test result, 4.6% in those with one nonreportable test result and 6.9% in those with a second nonreportable test result (aOR, 2.2 and 2.7; 95% CI, 1.4–3.4 and 1.2–6.0, respectively). Preeclampsia showed a similar trend, with rates climbing from 3.9% in those with a reported result to 9.4% with 1 nonreportable result and 16.8% with 2 (aOR, 1.4 and 2.0; 95% CI, 1.0–1.9 and 1.1–3.7, respectively). Chances of live birth were significantly reduced in pregnancies with a nonreportable results (aOR, 0.20; 95% CI, 0.13–0.30), with the chances decreasing more after a second nonreportable test result (aOR, 0.11; 95% CI, 0.06–0.23).

The study found that nonreportable cfDNA screening results are associated with an increased risk for aneuploidy, preterm birth, and preeclampsia, with a gradient of increased risk with a second failed test. This adds to literature with conflicting findings surrounding obstetrical complications in those with altered cfDNA levels and with most studies largely focused on characteristics that may be predictive of a nonreportable result rather than outcomes associated with nonreportable results. These results can inform clinicians who have patients with nonreportable test results in a way that may help them provide better care; future research should focus on more fully understanding the adverse outcomes associated with nonreportable tests to maximize this ability for clinicians in the future. Further research should also focus on specific populations or diagnoses to understand if there are fundamental differences in different groups of individuals.