Maternal plasma cell-free fetal and maternal DNA at 11-13 weeks' gestation: relation to fetal and maternal characteristics and pregnancy outcomes.

OBJECTIVE To examine the possible relationship between maternal and fetal characteristics and pregnancy outcomes on fetal and maternal cell-free (cf) DNA in maternal plasma at 11-13 weeks' gestation. METHODS cfDNA was extracted from maternal plasma of 1,949 singleton pregnancies and chromosome-selective sequencing was used to determine the proportion of cfDNA and total cfDNA counts which was of fetal and maternal origin. Multivariate regression analysis was used to determine whether specific maternal and fetal characteristics and pregnancy complications, such as preeclampsia (PE), early spontaneous preterm birth (SPB) and delivery of small for gestational age (SGA) neonates, were significant predictors of fetal and maternal cfDNA in maternal plasma. RESULTS The fetal and maternal cfDNA plasma concentration increased with serum pregnancy-associated plasma protein-A and free β-human chorionic gonadotropin level, was higher in women of Afro-Caribbean and East-Asian racial origin than in Caucasians, and lower in smokers, but it was not significantly altered in pregnancies complicated by PE, SPB or SGA. The fetal cfDNA level was inversely related to maternal weight and uterine artery pulsatility index, and maternal cfDNA increased with maternal weight. CONCLUSIONS The fetal and maternal cfDNA level in maternal plasma is affected by maternal and fetal characteristics, but it is not altered in pregnancy complications.