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.