Fetal fraction of cell-free DNA in maternal plasma in the prediction of spontaneous preterm delivery.

OBJECTIVES To investigate whether, in pregnancies complicated by spontaneous preterm delivery, fetal fraction of cell-free DNA (cfDNA) in maternal plasma at 11-13 weeks' gestation is altered and if this measurement could be useful in the prediction of preterm delivery. METHODS Fetal fraction of cfDNA was measured at 10 + 0 to 13 + 6 weeks' gestation in 3169 pregnancies, 3066 (96.7%) that delivered at ≥ 37 weeks and 103 (3.3%) with spontaneous delivery at < 37 weeks, including 21 that delivered at < 34 weeks and 82 that delivered at 34-37 weeks. The measured fetal fraction was converted to multiples of the median (MoM), corrected for maternal characteristics and gestational age, and the Mann-Whitney U-test was used to determine the significance of differences in the median values in the spontaneous preterm delivery groups from that in the term delivery group. RESULTS In the spontaneous preterm delivery groups (< 34 weeks' gestation, 34-37 weeks, < 37 weeks), compared to the term delivery group, there was no significant difference in the median fetal fraction MoM (1.004, 0.922 and 0.946, respectively, vs 1.015). CONCLUSION Measurement of fetal fraction in maternal plasma at 11-13 weeks' gestation is not predictive of spontaneous preterm delivery.