When should RhoGAM (Rho(D) immune globulin) be administered to Rh-negative pregnant women?

From the Guidelines

RhoGAM (Rho(D) immune globulin) should be administered to Rh-negative pregnant women at 28 weeks of gestation and again within 72 hours after delivery if the baby is Rh-positive, as well as after potentially sensitizing events such as miscarriage, abortion, ectopic pregnancy, amniocentesis, chorionic villus sampling, or abdominal trauma, ideally within 72 hours of the event, to prevent RhD alloimmunization and its associated risks 1.

Key Considerations

• The standard dose is 300 micrograms (μg) intramuscularly for pregnancies beyond 12 weeks, while a smaller dose of 50 μg (MICRhoGAM) is used for pregnancies less than 12 weeks 1.
• RhoGAM works by preventing Rh-negative mothers from developing antibodies against Rh-positive fetal blood cells that may enter maternal circulation during pregnancy or delivery.
• Without RhoGAM, these mothers can become sensitized and develop anti-Rh antibodies that could cross the placenta in subsequent pregnancies and attack the red blood cells of an Rh-positive fetus, potentially causing hemolytic disease of the newborn, which can lead to severe anemia, jaundice, or even fetal death.

Administration Guidelines

• For spontaneous or induced abortion at less than 12 weeks of gestation, a 50 mg dose of RhIg within 72 hours is adequate to cover the volume of potential feto-maternal hemorrhage in the first trimester 1.
• If the lower dose is unavailable, a 300 mg RhIg dose may be used.
• In cases where the supply of RhIg is limited, postpartum patients and antenatal patients at later gestational ages should be prioritized for the available doses 1.

Risks and Benefits

• The risks associated with RhIg administration are low, and prevention of RhD alloimmunization is critical to avoid the consequences of alloimmunization on pregnancy and perinatal outcomes 1.
• The consequences of RhD alloimmunization increase with each subsequent pregnancy and are associated with the need for fetal transfusion, fetal hydrops, stillbirth, preterm delivery, and hemolytic disease of the newborn 1.

From the FDA Drug Label

HyperRHO S/D Full Dose is recommended for the prevention of Rh hemolytic disease of the newborn by its administration to the Rho(D) negative mother within 72 hours after birth of an Rho(D) positive infant,(12) providing the following criteria are met: The mother must be Rho(D) negative and must not already be sensitized to the Rho(D) factor. HyperRHO S/D Full Dose should be administered within 72 hours to all nonimmunized Rho(D) negative women who have undergone spontaneous or induced abortion, following ruptured tubal pregnancy, amniocentesis or abdominal trauma unless the blood group of the fetus or the father is known to be Rho(D) negative. If HyperRHO S/D Full Dose is administered antepartum, it is essential that the mother receive another dose of HyperRHO S/D Full Dose after delivery of an Rho(D) positive infant.

RhoGAM (Rho(D) immune globulin) should be administered to Rh-negative pregnant women:

• Within 72 hours after birth of an Rh-positive infant
• Within 72 hours after spontaneous or induced abortion, ruptured tubal pregnancy, amniocentesis, or abdominal trauma, unless the blood group of the fetus or the father is known to be Rh-negative
• Antepartum, with another dose given after delivery of an Rh-positive infant 2 2

From the Research

Administration of RhoGAM

RhoGAM (Rho(D) immune globulin) is administered to Rh-negative pregnant women to prevent Rh alloimmunization. The guidelines for administration are as follows:

• At 28 weeks' gestation, a dose of 300 microg of RhoGAM should be given to all Rh-negative nonsensitized women when fetal blood type is unknown or known to be Rh-positive 3.
• After delivery, a dose of 300 microg of RhoGAM should be given within 72 hours to postpartum nonsensitized Rh-negative women delivering an Rh-positive infant 3.
• If anti-D is not given within 72 hours of delivery or other potentially sensitizing event, anti-D should be given as soon as the need is recognized, for up to 28 days after delivery or other potentially sensitizing event 3.
• Additional anti-D Ig may be required for fetomaternal hemorrhage (FMH) greater than 15 mL of fetal red blood cells 3.

Special Considerations

• After miscarriage or threatened abortion or induced abortion during the first 12 weeks of gestation, nonsensitized D-negative women should be given a minimum anti-D of 120 microg 3.
• After 12 weeks' gestation, they should be given 300 microg 3.
• Anti-D should be given to nonsensitized D-negative women following ectopic pregnancy, with a minimum of 120 microg given before 12 weeks' gestation and 300 microg after 12 weeks' gestation 3.
• Anti-D should be given to nonsensitized D-negative women following molar pregnancy because of the possibility of partial mole 3.

Dosage and Timing

• The dosage and timing of RhoGAM administration may vary depending on the specific clinical situation and the presence of fetomaternal hemorrhage 4.
• A minimum dose of 50 microg should be given before 20 weeks gestation, and 100 microg after 20 weeks gestation 4.
• The administration of RhoGAM should be done as soon as possible, but no later than 72 hours after the event 4.

Route of Administration

• RhoGAM can be administered via intramuscular (IM) or intravenous (IV) routes, with both routes being equally effective in preventing RhD alloimmunization 5.
• The choice of route of administration will depend on the available preparations, the dose to be administered, and patient preferences 5.

Efficacy of Antenatal Prophylaxis

• A single intramuscular injection of Rh immune globulin, 300 mug, is 88% effective in preventing Rh isoimmunization during pregnancy in Rh-negative primigravidas and in multigravidas treated antenatally in all previous pregnancies 6.
• The majority of failures are due to Rh isoimmunization during pregnancy prior to antenatal prophylaxis at 28 weeks 6.

Prevention of Alloimmunization

• Routine administration of RhIG at 26-30 weeks' gestation and again within 72 hours of delivery has been shown to be highly effective in preventing maternal Rh alloimmunization, with very low rates of D-antigen sensitization reported in multiple studies of at-risk women 7.
• The available RhIG products are not the same and should be carefully reviewed to ensure that they are administered safely 7.