Until recently, the obstetrician has had little to offer patients who were α- or β-thalassemia carriers or carriers of a gene for a structurally abnormal hemoglobin, to say little of hemophilia and other hematologic disorders. Such patients usually had uncomplicated pregnancies and the obstetrician's role was limited to genetic counseling and possibly performing abortions for those couples fearful of delivering an affected child. More recently, the development of methods to diagnose hemoglobinopathies in utero allows the obstetrician to give parents definite answers rather than statistical probabilities. Couples at risk can avoid having affected children without remaining childless and are spared the months of anxiety awaiting the outcome of a pregnancy. The purpose of this review is to consider the progress that permits the antenatal diagnosis of the hemoglobinopathies and other hematologic disorders.