For the first time, researchers have diagnosed fetal genetic disorders by taking blood samples from pregnant women, eliminating risk to the fetus. The new techniques rely on the fact that a very small number of fetal blood cells can make their way into a pregnant woman's bloodstream through leaks in the placenta.
The cells are very rare in the mother's bloodstream, however. The new technique described at the human genetics congress uses automated blood cell sorters to help separate fetal blood cells from maternal blood cells. Once the fetal cells were identified and separated, the genetic material in the cells was examined for abnormalities that would represent disorders in the fetus.