High levels of fetal DNA are associated with increased risk of spontaneous preterm delivery.

OBJECTIVE

To assess whether spontaneous preterm delivery can be predicted from the amount of cell free fetal DNA (cffDNA) as determined by routine fetal RHD genotyping at 25 weeks' gestation.

STUDY

DESIGN

Cohort study including RhD negative women participating in a routine RHD screening programme. A standard dilution curve was used to quantify the amounts of cffDNA. Values above the 95(th) centile for the study population defined high levels of cffDNA.

RESULTS

We found a highly significant association between preterm delivery and cffDNA levels above the 95(th) centile (p = 0.002). Using logistic regression, women with high levels of cffDNA had an odds ratio of 6.3 (95% confidence interval: 1.9-20.9) for preterm delivery before 37 weeks and an odds ratio for delivery before 34 weeks of 16.6 (95% confidence interval: 3.2-84.7) when adjusting for gestational age at sampling, body mass index and previous miscarriages/terminations of pregnancy.

CONCLUSION

High levels of cffDNA at 25 weeks are associated with increased risk of spontaneous preterm delivery.