What Rh Status Means in Pregnancy
Your RH status is very important for you and your baby. If you're RH-, then you will probably be advised to have a shot. Here's information on what that the Rhogam shot is, what being RH- in pregnancy is, and why you should research things before you consent to the shot.
Determining your blood type
The lab checks your blood type during your first round of prenatal testing (often called a “prenatal workup”). You learn what letter your blood type is (A, B, AB, and O). You also learn what your Rhesus, or RH, factor is. Your blood is either RH+, meaning the blood has the RH factor, or RH-, meaning the RH factor is not in your blood.
Some providers call the rH factor RH (D) positive or RH (D) negative.
There are six RH genes: C, D, E, c, d, and e.
The C, D, and E genes are positive RH genes; meaning there is an RH factor in the blood.
The c, e, and d genes are negative RH genes; meaning there is no RH factor in the blood.
Research shows only the “D” gene causes sensitivity issues, so it's the D gene that is of concern during your pregnancy. That's why some care providers call the RH factor RH (D) positive or RH (D) negative. You may also hear the shot given to RH- women (Rhogam) called Anti-D immunoglobulin.
Why does it matter if I have RH- or RH+ blood?
Bottom line: If you're RH- and your baby is RH+, there could be complications for your baby, or especially future babies.
If you're RH+ you don't have to worry, because your body doesn't mind an RH- fetus. If you're RH- and your baby's father is also RH-, then you probably don't need to worry. However, Natural Birth and Baby Care.com reader Sharon contacted me with this information after she and her husband, both Rh-, had an Rh+ baby:
From much research and meeting with genetics specialists…I discovered that you can have a positive baby, even if you are both negative parents.
In light of this information it's prudent to have your baby's cord blood typed even if both you and your baby's father are Rh-.
If you are RH- and your baby RH+, and your blood mixes with your baby's, it could become sensitized. Your body could begin producing antibodies to the RH+ blood. If these antibodies get to an unborn baby, they can begin killing off the baby's red blood cells. We call this RH disease. It is rare for it to affect a first baby, but if the mother becomes sensitized and produces antibodies to RH+ blood, it could cause problems for future babies. RH disease is very serious; however, recent medical advances allow 90% of babies with RH disease to survive (March of Dimes).
I have RH- blood. What can I do to keep my baby (and future babies) safe?
There is a shot available for women who are RH-. The shot is often called by the brand name Rhogam (BayRho-D is another brand). It is an Anti-D immunoglobulin. The shot is a processed human blood product containing antibodies to the RH factor. Injecting a small amount RH antibody into your blood sends it to work on any fetal blood cells in your bloodstream. This causes your body to think that the situation is under control and keeps you from producing antibodies on your own.
The shot was originally given within 72 hours of birth. Now it's common for care providers to give it routinely during pregnancy around 28 weeks. Some doctors are also giving it routinely at 36 weeks. It is also recommended after any type of “trauma” that could cause maternal and fetal blood to mix. Examples of such trauma are miscarriage, abortion, amniocentesis, CVS, car wreck, falling on your belly, etc.
This sounds great! Why should I think twice about the shot?
The shot is a human blood product. There are some possible side effects to the shot, including possible effects on the immune system of mother and child. The manufacturer screens the shot for all diseases possible to screen for and the reaction rate is low. Nevertheless, these risks do exist. Some companies preserve Anti-D immunoglobulin shots in mercury, which is another concern. There are mercury-free versions available (BayRho and RhoGAM; RhoGAM is also latex free.)
The Anti-D shot is only effective within 72 hours of maternal-fetal blood mixing. So even if the injection is given at 28 weeks, it will only help if maternal and fetal blood has mixed 72 hours or less before the injection. The Rhogam manufacturer states that an injection every 12 weeks will keep up a “passive immunity,” meaning that theoretically a shot every twelve weeks protects you during trauma causing your and your baby's blood to mix. They still recommend a new shot at the time of blood mixing if >15mL of exposure has occurred.
Normally maternal and fetal blood flows side by side at the placenta, but never actually mixes. Maternal and fetal blood don't mix during the course of normal, physiologic childbirth. It's usually during childbirth with intervention that blood mixes. Interventions could be forceps, episiotomy, cord traction (pulling on the umbilical cord to get the placenta out), or cesarean section, among others. Amniocentesis, CVS, hard falls, car accidents, miscarriage, or abortion, among others, could cause maternal and fetal blood to mix.
In a natural childbirth where the third stage of labor progresses gently (no forcing the placenta to come), it's very rare for the blood of mother and baby to mix. A homebirth with no medical intervention is often the safest way to assure that maternal and fetal blood does not mix.
If the baby is born RH-, there is no danger of the mother becoming sensitized and so Anti-D is not needed.
So what should I do?
Some women choose to get all the Anti-D injections their care providers give routinely for the peace of mind that they get from it.
Other women choose to completely forgo any shots, not wanting to introduce human blood products into their bodies or their baby's body. They also don't want to risk the possible side effects of the shot.
Some women don't get the shot in the prenatal period. After the baby is born, the woman has the baby's blood tested. If the baby is RH+, she's injected with Anti-D immunoglobulin (Rhogam). It is important that the shot be given within 72 hours after birth, so the lab should test your baby's blood immediately. Blood taken from the umbilical cord works perfectly for the test.
Some women opt for the injection either prenatally and postpartum, or only postpartum, but ask that a mercury-free version be administered.
Some women decline prenatally but go in for the shot if they've been in an accident or need a medical procedure that could cause mixing of maternal and fetal blood.
Some women choose to have a test done on their own blood, called and Indirect-Coombs. This test will show whether sensitization has happened or not. They may have it done before and during pregnancy, so that they know exactly what is happening with their body.
A hard choice for some.
Some women have a hard time deciding what to choose when it comes to their RH status and the shots. They may want to do everything they can to protect future children, but be unsure how effective a shot given routinely in the prenatal period really is. And they may feel uncomfortable having a human blood product injected into their body while they have an unborn baby in the womb.
It's not an easy choice to make. It deserves careful consideration and weighing all the risks and benefits.
- Find out Your Baby's rH Status During Pregnancy
- Common Prenatal Tests
- Preparing for a Gentle Childbirth
Some other resources for you to read (please note I wrote only one of these; I express no agreement or disagreement with the other sources – I offer them for your information):
- Prenatal Rhogam: Examining Reality – an article I wrote for VegFamily magazine.
- The Wikipedia has some information on Rhogam and possible side effects