Quantification of cell free fetal DNA in maternal plasma in normal pregnancies and in pregnancies with placental dysfunction.

OBJECTIVE To assess the normal levels of free fetal DNA in maternal plasma through pregnancy compared with those in pregnancies complicated with placental dysfunction manifested by preeclampsia and/or fetal growth restriction. STUDY DESIGN Maternal blood samples from 138 singleton male pregnancies were divided into 3 groups; normal pregnancies (77), preeclampsia (49), and fetal growth restriction (12). Royston and Wright's methods were used to calculate gestational age-related reference limits of free fetal DNA in the 3 groups. The DYS14 gene of the Y chromosome was quantified and compared in maternal plasma by using real-time quantitative polymerase chain reaction. RESULTS Free fetal DNA in normal pregnancies increased with gestational age. Results were significantly higher in preeclampsia and fetal growth restriction groups than in normal pregnancy and were higher in severe preeclampsia than in milder disease. CONCLUSION Free fetal DNA is a potential marker for placental dysfunction in pregnancy. Large prospective studies are now needed to investigate its role in the prediction of pregnancy complications and severity and or timing of delivery.