Non-invasive prenatal diagnosis and testing by analysis of cell-free DNA in the 
maternal circulation is a rapidly evolving field. Current clinical applications 
include fetal sex determination, fetal rhesus D determination, the diagnosis of 
some single gene disorders, and a highly accurate screening test for 
aneuploidies. In the future it is likely to be used for the diagnosis of an 
increasing range of monogenic disorders, and may even be used to profile entire 
fetal genomes. The introduction of these tests into clinical practice brings 
clear benefits but also poses several ethical, social and service delivery 
challenges. Here, we discuss the current clinical applications, discuss some of 
the technical and ethical challenges, and look to what the future might bring as 
technology continues to evolve.