The effects of heparin, aspirin, and maternal clinical factors on the rate of nonreportable cell-free DNA results: a retrospective cohort study

BACKGROUND: Technological advances in the analysis of cell-free DNA in maternal serum have allowed expanded prenatal screening possi-bilities for fetal aneuploidies. The sensitivity and positive predictive value of the assay are partly dependent on the amount of cell-free DNA present in maternal circulation. Thus, it is important to know what fetal and mater -nal factors influence the level of cell-free DNA in maternal circulation. Maternal heparin use has been associated with an increase in nonreport-able cell-free DNA results because of a low fetal fraction in some, but not all, previous studies. In addition, there are likely additional factors that affect cell-free DNA that remain uncharacterized.OBJECTIVE: This study aimed to determine whether heparins, low-dose aspirin, and maternal clinical factors affect the rate of nonreportable cell-free DNA testing results.STUDY DESIGN: A retrospective cohort study was conducted using pregnant people receiving cell-free fetal DNA testing from January 1, 2014, to June 30, 2018. Data were collected on patient demographics, medical comorbidities, medication use, and cell-free DNA test results. Uni-variate and multivariate analyses were performed to determine which fac-tors were independently associated with the rate of nonreportable results.RESULTS: From an original sample of 1117 pregnant people, 743 met the inclusion criteria. Maternal weight (odds ratio, 1.02), heparin use (odds ratio, 12.06), aspirin use (odds ratio, 4.70), chronic hypertension (odds ratio, 5.26), pregestational diabetes mellitus (odds ratio, 2.46), and autoimmune disease (odds ratio, 3.59) were significantly associated with an increased rate of nonreportable results in the univariate analysis. More -over, the association was present for maternal weight (odds ratio, 1.02), heparin use (odds ratio, 21.87),and aspirin use (odds ratio, 2.85) in the multivariate analysis.CONCLUSION: The previously seen association between maternal heparin use and an increase in nonreportable cell-free DNA results was confirmed. Furthermore, there seems to be an increase in nonreportable results in pregnant people taking low-dose aspirin. Providers should con -sider the effect of these medications when counseling patients on prenatal genetic screening options.