Abstract: Cell-free fetal DNA (cffDNA) has been successfully detected in maternal circulation during pregnancy. Unlike intact fetal cell in maternal circulation, cffDNA can be detected from 4 weeks gestations and cleared from the circulation following birth. The source of cffDNA has not been clearly elucidated and speculated from placenta with the mechanism of apoptosis. The usage of cffDNA can be applied to diagnose fetal aneuploidy during first and second trimester pregnancy. The limitation of cffDNA is the scarcity in maternal circulation to challenge the measurements. Nowadays some new detecting methods have been developed and applied to the prenatal diagnosis, but still need to be improved. The development of cffDNA will offer a good application prospect for non-invasive prenatal diagnosis of aneuploidy.

Key words: Cell-free DNA, Fetal, Non-invasive prenatal diagnosis, Aneuploidy