Generalized edema from fluid collection in the soft tissues results in hydrops fetalis. There are many causes for fetal hydrops. The most common are "non-immune" types that include infections, congestive failure (from anemia or cardiac abnormalities), and congenital anomalies. Immune hydrops, from maternal antibody formed against fetal red blood cells, is not common when Rh immune globulin is employed in cases of potential Rh incompatibility.