When is RhoGAM (Rho(D) immune globulin) given to pregnant women?

When to Administer RhoGAM (Rh(D) Immune Globulin) in Pregnancy

RhoGAM should be administered to unsensitized Rh-negative women at 28 weeks gestation, within 72 hours after delivery of an Rh-positive infant, and following any potentially sensitizing event including spontaneous or induced abortion, regardless of gestational age. 1

Standard Prophylaxis Protocol

• RhoGAM should be administered to all unsensitized Rh-negative pregnant women at 28 weeks gestation when fetal blood type is unknown or known to be Rh-positive 1
• A second dose should be given within 72 hours after delivery if the infant is Rh-positive 1, 2
• This two-dose protocol reduces the rate of RhD alloimmunization from approximately 1.8% to between 0.1% and 0.2% 1, 3
• Postpartum RhoGAM alone decreases the rate of anti-D alloimmunization from 13-17% to 1-2% 1, 2

Administration for Pregnancy Complications

• Spontaneous or Induced Abortion:

  • For abortions before 12 weeks gestation: A minimum dose of 50 μg RhoGAM within 72 hours is adequate 1
  • For abortions after 12 weeks gestation: A standard 300 μg dose should be given 1, 4
  • The Society for Maternal-Fetal Medicine recommends offering both RhD testing and RhoGAM for spontaneous and induced abortion at <12 weeks gestation despite some conflicting guidelines 5

• Threatened Abortion/Vaginal Bleeding:

  • RhoGAM should be administered in cases of threatened abortion with heavy bleeding, abdominal pain, or when the event occurs near 12 weeks 1
  • For bleeding events before 12 weeks gestation, a minimum dose of 50 μg RhoGAM within 72 hours is adequate 1

• Invasive Procedures:

  • After amniocentesis: 300 μg dose 1, 4
  • After chorionic villus sampling: 120 μg during first 12 weeks, 300 μg after 12 weeks 4
  • After cordocentesis: 300 μg 4

• Other Indications:

  • Ectopic pregnancy: 120 μg before 12 weeks, 300 μg after 12 weeks 4
  • Molar pregnancy: RhoGAM should be given due to possibility of partial mole 4
  • Minor trauma in pregnancy: Consider RhoGAM as 28% of pregnant patients with minor trauma have fetomaternal hemorrhage 1

Special Considerations

• If RhoGAM is not given within 72 hours of a potentially sensitizing event, it should still be administered up to 28 days after the event 4
• For large fetomaternal hemorrhage (>15 mL of fetal red blood cells), additional doses of RhoGAM may be required 2, 4
• Women with "weak D" (Du-positive) should not receive RhoGAM 4
• If RhoGAM supply is limited, postpartum patients and antenatal patients at later gestational ages should be prioritized 1

Mechanism and Rationale

• Fetal RBCs display red cell antigens from as early as 6 weeks gestation, making maternal sensitization possible even in early pregnancy 5, 1
• RhoGAM suppresses the maternal immune response to fetal RhD-positive red blood cells, preventing the production of anti-D antibodies 2
• Prevention of alloimmunization is critical given its substantial impact on pregnancy outcomes including hemolytic disease of the fetus/newborn, need for fetal transfusion, fetal hydrops, and stillbirth 1

Common Pitfalls to Avoid

• Failing to administer RhoGAM in early pregnancy based on misconceptions that sensitization cannot occur before 12 weeks 5, 1
• Not recognizing that a large fetomaternal hemorrhage may require additional doses of RhoGAM 2
• Overlooking the need for RhoGAM in cases of minor trauma during pregnancy 1
• Administering RhoGAM to women with "weak D" (Du-positive) who do not require it 4
• Delaying administration beyond 72 hours, though it may still be beneficial up to 28 days after exposure 4