Fetal cells in maternal circulation during pregnancy constitute a potential source for safe and reliable non inva­sive prenatal diagnosis, and many approaches have been designed for their isolation and enrichment. Their exis­tence has been conclusively demonstrated with the advent of sensitive molecular techniques of genetic analysis, and they can be used for the identification of fetal chromo­some aneuploidies and inherited genetic disorders. How­ever, due to their scarcity and the lack of specific mono­clonal antibodies even the best current enrichment strate­gies result in preparations which contain only few fetal cells surrounded by a large number of maternal ones. It is hoped and expected, however, that continuous research will improve and facilitate the clinical application for non invasive prenatal diagnosis.

Key words: Fetal cells in maternal circulation; Non invasive prenatal diagnosis; Nucleated red blood cells (NRBC).