Anti-D Immunoglobulin Management for Rh-Negative Mothers

Understanding Rh Alloimmunization Risk

The RhD antigen is well-developed by 6 weeks' gestation and can be detected in fetuses as young as 38 days, with fetomaternal hemorrhage (FMH) occurring in approximately 50% of all deliveries, allowing fetal red cells to enter maternal circulation 1
As little as 0.1 mL of Rh-positive fetal cells can cause alloimmunization in an Rh-negative mother, and without anti-D prophylaxis, approximately 17% of Rh-negative women will become immunized after pregnancy with an ABO-compatible, Rh-positive infant 1
The introduction of postpartum Rh prophylaxis programs reduced fetal mortality from Rh hemolytic disease from 120 per 100,000 live births to 1.5 per 100,000 by 1989, highlighting the importance of anti-D immunoglobulin management 3

For a second gravida mother, the risk of Rh alloimmunization is particularly important, as any sensitization from the first pregnancy may lead to a more robust immune response, with antibody levels from a first pregnancy potentially being insufficient to detect until an anamnestic response occurs in a second Rh-positive pregnancy 1, 2

Antenatal prophylaxis with anti-D immunoglobulin at 28 weeks' gestation (300 μg) reduces the immunization rate by approximately 90% beyond what is achieved with postpartum prophylaxis alone, according to the American College of Obstetricians and Gynecologists 3