Rhesus D Prophylaxis: When and Why We Give Rhesus D Immunoglobulin

Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal alloantibodies to fetal red blood cells and is associated with significant fetal and neonatal morbidity and mortality. Rhesus D antigen (RhD)-mediated HDFN is the only preventable cause of alloimmunization in pregnancy. Widespread utilization of RhD prophylaxis reduces the risk of RhD-mediated alloimmunization from 17% to <1% in at-risk pregnancies, although RhD-mediated HDFN still occurs.

To emphasize significance of RhD prophylaxis, outline current guideline-directed indications for administration, provide clarification in areas of uncertainty regarding prophylaxis administration, and review key concepts relevant to patient education and shared decision-making.

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Data over several decades have shown implementation of prenatal and postpartum RhD prophylaxis has significantly reduced incidence and morbidity of RhD-mediated HDFN. Most international guidelines recommend routine prophylaxis of Rh-negative mothers in the second trimester and peripartum, with additional prophylaxis following certain high-risk events. Recent shortages in RhD immunoglobulin (RhDIg) and new methods to determine fetal blood type have prompted renewed debate regarding criteria for prophylaxis during the first trimester.

Understanding indications for administration of RhD prophylaxis is essential for preventing RhD alloimmunization. Although uncertainty remains in some clinical scenarios, prophylaxis is strongly recommended in Rh-negative mothers in the second trimester, following events high-risk for sensitization in pregnancy, and postpartum.

In this review, the etiology of alloimmunization and indications for RhDIg prophylaxis, current society recommendations, and areas of debate are summarized and discussed.