Is antenatal RhIg completely safe?

Abstract

The administration of antenatal and postnatal Rh immunoglobulin prophylaxis significantly prevents Rh D alloimmunization during pregnancy. A dose of 20 g anti-D IgG protects against 1 mL of D-positive red blood cells or 2 mL of whole blood. Rh D-negative women if unsensitized receive antenatal anti-D prophylaxis of 300 g at 28 weeks of pregnancy and postnatal prophylaxis if the baby is Rh D positive. Initial trials concluded that postpartum immunoprophylaxis decreased the incidence of Rh D immunization from 12–13% to 1–2% which was further shown to be reduced to 0.1% thanks to antenatal prophylaxis.1 Rh immunoglobulin (RhIg) administration is quite safe during pregnancy although RhIg can cross the placenta and cause hemolysis of the red cells of D-positive fetuses. Unfortunately data is sparse on this serious adverse event. Herein we present an unusual case of hemolytic disease of newborn (HDN) with positive Direct Coombs’ Test (DCT) due to antenatal RhIg prophylaxis in an Rh-negative mother.