Rh disease
Rh disease (also known as rhesus isoimmunization, Rh (D) disease, or rhesus incompatibility, and blue baby disease) is a type of hemolytic disease of the fetus and newborn (HDFN). The term "Rh disease" is commonly used to refer to HDFN as prior to the discovery of anti-Rho(D) immune globulin, it was the most common type of HDFN. The disease ranges from mild to severe, and occurs in the second or subsequent pregnancies of Rh-D negative women when the biological father is Rh-D positive due to the presence of anti-D antibodies (the D antigen being only one of more than 50 in the Rh complex).