Fraction of cell‐free fetal DNA in the maternal serum as a predictor of abnormal placental invasion‐a pilot study

OBJECTIVE: Pilot studies have suggested the amount of cell-free fetal DNA (cffDNA) in the maternal serum is increased in pregnancies complicated by placenta accreta. Our objective was to determine if levels of cffDNA can predict invasive placentation. METHODS: We enrolled women with antenatally suspected placenta accreta compared with gestational age-matched cases of placenta previa and women with prior cesarean deliveries (CDs) and normal placentation. The fetal fraction of cffDNA was quantified using DANSR™ as compared with total DNA. Patient characteristics were compared between the three groups using ANOVA, and linear regression was used to compare the fraction of cffDNA between pathologically confirmed cases of placenta accreta, placenta previa and normal placentation. RESULTS: Twenty women were enrolled, (seven cases of placenta accreta, six cases of placenta previa and seven cases of normal placentation with prior CD). The groups did not differ by maternal weight, placental weight, number of prior CD or years from prior CD. The mean fraction of cffDNA did not differ significantly by group when controlling for the aforementioned factors (accreta = 19.1%, previa = 27.2%, prior CD = 28.9%, p = 0.26), nor did the median (accreta = 17.0%, previa = 30.1%, prior CD = 22.7%). CONCLUSIONS: We could not confirm diagnostic benefit. Further investigation of other biomarkers including placental mRNA is warranted.