Abstract: Traditional prenatal diagnosis depends on invasive manipulations, which have potential risks for fetus. Nowadays the technologies of non-invasive prenatal diagnosis （NIPD） focus on isolation of fetal intact cells from maternal circulation and extraction of cell-free fetal DNA, but these two methods have limitations in clinical applications. Recently the foundation of cell-free RNA in maternal blood has become a great breakthrough in NIPD. The cffRNA has been proved to origin from placenta, and easy to detect due to stable characteristics. The cffRNA has more advantages in clinical applications than cffDNA because the former does not need to depend on fetal gender or paternal polymorphic markers. The preliminary accomplishment has been made in prenatal diagnosis of Down syndrome through the combination with quantitative methods for molecular markers. The development of cffRNA will offer a good application prospect for NIPD of aneuploidy.

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