In pregnant patients, the impact of blood type and the presence of red blood cell antibodies influence the course of the pregnancy and the health of the fetus and newborn infant. Throughout history, haemolytic disease of the fetus and newborn has played a fundamental role in the discovery of the blood group antibodies and their cognate antigens. The mid‐1900s were noted for the advent of Rh immunoglobulin. Now, the technological advancements in diagnosis and treatment of haemolytic disease of the fetus and newborn have provided the critical tools needed to support mothers with affected pregnancies. The knowledge of blood typing has been further refined with the explosion of understanding about blood group genes, particularly in the RH blood group. Genomic blood group typing, improvements in ultrasound technology and transfusion medicine progress have advanced the field. The care of women with potentially affected pregnancies has never been more robust. Despite this, the risk to the fetus is significant, and prevention strategies for maternal alloimmunization deserve continued attention.