Total and fetal cell-free DNA analysis in maternal blood as markers of placental insufficiency in intrauterine growth restriction.

OBJECTIVE: To compare total and fetal DNA levels in the maternal plasma in three groups: pregnancies with intrauterine growth restriction (IUGR) due to placental insufficiency (PI) and other causes, and in control pregnancies. METHODS: Total as well as fetal DNA was quantified in 78 maternal plasma samples. In 19 pregnancies, the fetus presented IUGR due to PI (group A), and in 31 pregnancies due to other causes (group B). The control group comprised 28 patients (group C). DNA quantification was done using real-time quantitative PCR with a standardized pool of plasmid calibrators. DNA concentrations of the three groups were compared using non-parametric tests (Kruskal-Wallis or Mann-Whitney tests). RESULTS: The three groups did not statistically differ regarding maternal age (mean +/- SD: 30.5 +/- 5.4 years), gestational age (30 +/- 5.3 weeks) or the proportion of male fetuses (48.2%). Plasma total DNA was significantly higher in group A compared to groups B and C (p = 0.001 for both). An increase in fetal DNA was only observed in group A for patients beyond 28 weeks of gestation. CONCLUSIONS: The plasma total DNA level is higher in patients with IUGR due to PI. These results suggest the presence of maternal endothelial damage independently of preeclampsia.