The collection of fetal genetic materials is required for the prenatal diagnosis 
of fetal genetic diseases. The conventional methods for sampling fetal genetic 
materials, such as amniocentesis and chorionic villus sampling, are invasive in 
nature and are associated with a risk of fetal miscarriage. For decades, 
scientists had been pursuing studies with goals to develop non-invasive methods 
for prenatal diagnosis. In 1997, the existence of fetal derived cell-free DNA 
molecules in plasma of pregnant women was first demonstrated. This finding 
provided a new source of fetal genetic material that could be obtained safely 
through the collection of a maternal blood sample and provided a new avenue for 
the development of non-invasive prenatal diagnostic tests. Now 15 years later, 
the diagnostic potential of circulating fetal DNA analysis has been realized. 
Fruitful research efforts have resulted in the clinical implementation of a 
number of non-invasive prenatal tests based on maternal plasma DNA analysis and 
included tests for fetal sex assessment, fetal rhesus D blood group genotyping 
and fetal chromosomal aneuploidy detection. Most recently, research groups have 
succeeded in decoding the entire fetal genome from maternal plasma DNA analysis 
which paved the way for the achievement of non-invasive prenatal diagnosis of 
many single gene diseases. A paradigm shift in the practice of prenatal 
diagnosis has begun.