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Informed Choice for Administration of Rh Immune Globulin in Pregnancy
What does it mean to be Rh negative?
Human blood can be divided into four major types: A, B, AB, and O. These types are named based on the presence or absence
of two different markers, A and B, on the surface of the red blood cells. People with the A marker only have type A blood; those
with the B marker only have type B blood; those with both the A and B markers have type AB blood; and those with neither A nor
B are type O. Red blood cells can also contain several other factors, including Rh factor. Individuals who have red blood cells
with the Rh factor are considered Rh positive (Rh+) and those without the factor are Rh negative (Rh-). A person’s blood type is
described based on the presence or absence of A, B, and Rh factor. For example, a person who is O+ has type O blood that
contains the marker for Rh factor.
The presence of Rh factor is affected by racial background. Only approximately 1% of Asian-Americans are Rh-, whereas 8% of
African-Americans and 13% of white Americans are Rh-.
Why does Rh factor matter?
Our immune systems are made to recognize and destroy foreign substances, such as viruses and bacteria, in the body. The
surfaces of viruses and bacteria contain chemicals called antigens. The first time you are exposed to a particular antigen, your
immune system creates antibodies to get rid of that specific antigen. Some of these antibodies stay in the immune system and
remain ready to eliminate the antigen the next time you are exposed. This process of creating antibodies for specific antigens is
called sensitization.
If an Rh- woman is exposed to Rh+ blood, such as by being pregnant with a baby who is Rh+, sensitization may occur during
pregnancy or labor if there is any mixing of the blood. Usually, this does not cause any problem for the baby the first time it
occurs. If, however, the mother does become sensitized during one pregnancy, her body will produce antibodies that can cross
the placenta and destroy the red blood cells of any future Rh+ babies she carries. This can lead to severe anemia in the baby,
which can then lead to congestive heart failure and death.
Does this affect Rh+ moms?
Because Rh- blood does not contain the Rh factor, it will not cause any reaction in moms with Rh+ blood. Sensitization will not
occur.
How does sensitization occur?
In order for an Rh- woman to become pregnant with an Rh+ baby, the father of the baby must be Rh+ (except in very rare cases
of genetic mutation). When the mom is Rh- and the father is Rh+, the baby may be either Rh+ or Rh-.
Exposure can occur during a normal pregnancy with an Rh+ baby, but is more likely to occur if there is any sort of trauma, such
as miscarriage, abortion, amniocentesis, abuse, or a car accident. It can also occur during labor with an Rh+ baby. Sensitization
does not occur every time an Rh- mom is exposed. During pregnancy there is a 2% chance of sensitization. During labor this
chance rises to 13-16%.
Can I find out if my baby is Rh+?
Finding out whether a fetus has Rh- or Rh+ blood requires invasive procedures that can affect the fetus. These procedures are
performed only when necessary for the health of the fetus, and not to find out the fetus’s blood factor. After the baby is born,
however, a blood sample can be taken from its umbilical cord and sent to a lab to determine its Rh factor.
How does being Rh- affect my prenatal care?
You can have your blood drawn to determine your blood type and factor and to assess whether or not sensitization has occurred.
This is routinely done at your initial prenatal visit. If sensitization has occurred (i.e., there are antibodies to Rh factor in your
blood), you may be referred to an obstetrician. If sensitization has not occurred and there is a possibility that the fetus is Rh+
(i.e., the father of the baby is Rh+), it is recommended that your blood be drawn again at 28 weeks gestation to check for
sensitization. If sensitization has not occurred by 28 weeks, you have the option of receiving Rh immunoglobulin (RhIG) to
decrease your risk of sensitization. RhIG is only effective if sensitization has not occurred. It works to destroy any fetal blood
cells in the mother’s body before her immune system develops Rh+ antibodies. RhIG is generally given as an injection into
muscle, either of the upper arm, upper thigh, or the buttocks.
If you choose not to receive RhIG at 28 weeks, the medical community recommends that you have your blood drawn again at 36
weeks to check for sensitization.
June 26, 2005
Informed Choice for Administration of Rh Immune Globulin in Pregnancy
When is RhIG given?
It is recommended that RhIG be given in any of the following situations to decrease the risk of sensitization:
 At 28 weeks gestation
 Within 72 hours after birth
 After any miscarriage, abortion, or ectopic pregnancy
 After any invasive procedure that may involve bleeding (amniocentesis, CVS, PUBS)
 After any injury to the mom, especially to the abdomen
 After any slight placental abruptions during pregnancy, evidenced by bleeding
 After an external version to turn a breech baby
How does being Rh- affect my postpartum care?
It is recommended that both your blood and the baby’s blood be tested after birth (by drawing blood from the mom and by taking
baby’s blood from the umbilical cord) to confirm blood type and factor and to check for the presence of antibodies. This is
standard in both the medical community and the midwifery community in Maine. If the baby’s blood is Rh-, there is no risk of
sensitization! If, however, the baby’s blood is Rh+ and your blood still shows no signs of sensitization, it is recommended that
you receive an injection of RhIG within 72 hours after birth to decrease the risk of sensitization. If the baby’s blood contains Rh+
antibodies, it should be monitored carefully and have its hemoglobin checked after birth and every few days to rule out hemolytic
anemia.
What are the benefits of RhIG?
Without RhIG, the risk of sensitization after pregnancy with an Rh+ baby is 13-16%. Receiving RhIG within 72 hours after birth
reduces this risk to 1-2%. This risk is further reduced by also receiving RhIG at 28 weeks gestation, and after any trauma or
invasive procedure during pregnancy.
What are the risks of RhIG?
The safety of RhIG for the fetus has not been clearly demonstrated. One concern is that it is prepared from human plasma. While
donor plasma is screened for a variety of markers, including those for HIV and hepatitis B and C, there is still a risk that it may be
contaminated with a virus. Another concern is that the leading form of RhIG – RhoGam – contains preservatives, including
thimerosol, which is derived from mercury. These preservatives can cause an allergic reaction, ranging from soreness at the
injection site, to a slight fever, to, more rarely, a potentially life-threatening anaphylactic reaction.
What other options do I have?
You can choose to receive a mercury-free form of RhIG, such as WinRho SD or BayRho-D. These forms are more expensive
and more difficult to obtain.
You can choose to receive RhIG only after the baby’s birth. This eliminates any risk to the baby from RhIG. If you are carrying an
Rh+ baby and receive RhIG only after birth, your risk of becoming sensitized is 1-2%. In most cases this will have little or no
affect on the current pregnancy, but could lead to significant problems in a subsequent pregnancy with an Rh+ baby. These
problems include mild to severe anemia, which can lead to congestive heart failure and death.
You can choose to not receive RhIG at all. In general, your risk of sensitization without an RhIG is 13-16%. This most likely will
not affect your current pregnancy, but if sensitization does occur, it could lead to significant problems in a subsequent pregnancy
with an Rh+ baby. Even if you do not plan to have more children and therefore, do not need RhIG, it is important to remember
that people’s lives change constantly and you may feel differently in the future.
June 26, 2005
Informed Choice for Administration of Rh Immune Globulin in Pregnancy
My choice
I have read the informed choice on administration of Rh immunoglobulin (RhIG) and choose the following:
_____ I choose to receive RhIG both prenatally, around 28 weeks, and postpartum, within 72 hours after birth, if my baby is Rh+.
_____ I choose to receive RhIG postpartum only, within 72 hours after birth, if my baby is Rh+. I decline prophylactic RhIG
prenatally.
_____ I decline administration of RhIG both prenatally and postpartum. I understand that if my baby is Rh+, I may become
sensitized and this could affect future pregnancies.
If I have chosen to receive RhIG, I choose to receive the following brand:
_____ RhoGam
_____ WinRho SD _____ BayRho-D
____________________________________________
Mother
_____________________________
Date
____________________________________________
Midwife
_____________________________
Date
June 26, 2005