http://news.bbc.co.uk/2/hi/health/7742873.stm
A new serum testing technique allows researchers to compare the mothers genes with the child's, and get a better idea if the child will inherit any of several hereditary diseases. In Britain 1/25 people carries the gene for cystic fibrosis. Up until now the only way to test for CF in a fetus was amniocentesis. The new genetic testing can also detect beta thalassemia or sickle cell disease.