Rh immune globulin contains
antibodies to the
Rh factor in blood. The antibodies come from donors
who have become
sensitized to the Rh factor. Giving these Rh
antibodies to an Rh-negative pregnant woman prevents her
immune system from producing its own Rh antibodies,
which would attack her Rh-positive fetus's red blood cells.
When introduced into an Rh-negative mother's bloodstream, Rh immune
globulin antibodies locate any Rh-positive fetal red blood cells that are
present. The antibodies attach to the Rh-positive red blood cells, masking
their presence from the mother's immune system. Although the Rh immune globulin
antibodies destroy fetal red blood cells, not enough are destroyed to harm the
Rh immune globulin is given by injection into a muscle
(intramuscular, or IM).
Rh immune globulin is given to all Rh-negative women who may be
carrying an Rh-positive fetus. While it prevents Rh
sensitization, Rh immune globulin cannot prevent damage to an Rh-positive fetus
if the mother is already sensitized to the Rh factor.
Rh immune globulin should be given to an Rh-negative woman to
Rh immune globulin is highly successful at preventing sensitization
in a current pregnancy. When given at 28 weeks and within 72 hours of delivery
of an Rh-positive child, it has a success rate of greater than 99%.1
Side effects from Rh immune globulin are extremely rare and
Rh immune globulin does not carry a risk of
human immunodeficiency virus (HIV) or other types of
See Drug Reference for a full list of side effects. (Drug Reference
is not available in all systems.)
Although Rh immune globulin is not given to a woman who has become
sensitized to the Rh factor, it is not harmful to a
The dosage of Rh immune globulin can be adjusted to protect against
exposure to varying amounts of Rh-positive blood. Exposure to large amounts of
Rh-positive blood—caused by an injury, accidental transfusion with Rh-positive
blood, or complication during labor and delivery—will require a higher dose of
Rh immune globulin. A smaller-than-average dose may be given after an ectopic
pregnancy, molar pregnancy, induced abortion, or miscarriage (spontaneous
abortion) in early pregnancy.
If given within 3 months of a live virus
immunization, Rh immune globulin may block the benefit
of the immunization. Your doctor will be able to tell you whether you need
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CitationsAmerican College of Obstetricians and Gynecologists
(1999, reaffirmed 2010). Prevention of Rh D alloimmunization. ACOG Practice Bulletin No. 4.
Obstetrics and Gynecology, 93(5):
October 20, 2011
Sarah Marshall, MD - Family Medicine & William Gilbert, MD - Maternal and Fetal Medicine
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