A Noninvasive Test for Fetal RHD Genotype

In the United States and Canada, routine obstetrical care includes a blood test to determine the blood type of the mother (ABO and RhD). An antibody screen for anti-red cell antibodies in the mother's serum is also performed. Postpartum prophylactic treatment of RhD negative women with anti-D immunoglobulin to prevent "RhD Disease", or hemolytic disease of the fetus/newborn, was initiated in the 1960's. In the mid 1980's, the routine administration of antenatal anti-D immunoglobulin became the standard of care as well. Although these treatments have dramatically reduced the incidence of RhD Disease, approximately 40% of all RhD negative pregnancies continue to receive unnecessary injections of antenatal anti-D immunoglobulin. Genotyping platforms such as MALDI-TOF mass spectrometry allow for precise and sensitive detection of fetal-specific (paternally derived) alleles in maternal plasma. In this study, Sequenom's MassARRAY technology will be used to assess a noninvasive test for fetal RHD genotyping in a clinical setting.