What is the Rh factor?
Your Rh factor is an inherited protein on the surface of your red blood cells. If your red blood cells have this protein, you are Rh positive. If they don't, you are Rh negative. This factor, along with the ABO blood type system, determines your full blood type, such as A+, O-, or B+.
The Rh factor's discovery was a major step forward in understanding blood compatibility, particularly in transfusions and pregnancy. While the Rh positive type is more common, being Rh negative is a normal genetic variation and not a medical condition in itself.
Rh factor and general health
For the vast majority of people, being Rh negative has no bearing on their day-to-day health. It does not cause symptoms, illness, or general health complications. There is no special diet, exercise regimen, or lifestyle change required solely because of your Rh status.
The most important consideration for an Rh negative individual's health is in the context of blood transfusions. For safety, an Rh negative person should only receive Rh negative blood to prevent an immune system reaction. This is standard procedure in all medical settings and is routinely checked before any transfusion.
The critical connection: Rh factor and pregnancy
The main health risk associated with being Rh negative occurs during pregnancy. This risk arises when an Rh negative person is carrying an Rh positive fetus, a condition known as Rh incompatibility.
How Rh incompatibility develops
During pregnancy, a small amount of the fetus's blood can cross into the pregnant person's bloodstream. If the fetus is Rh positive, the Rh negative parent's immune system may perceive the Rh protein as a foreign invader. In response, the body develops antibodies to attack the foreign Rh positive cells. This process is called Rh sensitization.
In a first pregnancy, this sensitization often occurs late, usually during labor and delivery when the mixing of blood is most common. As a result, the first Rh positive baby is rarely affected. However, the antibodies remain in the parent's system. In a subsequent pregnancy with another Rh positive baby, the antibodies can cross the placenta and attack the fetus's red blood cells.
Potential complications for the fetus
If untreated, Rh incompatibility can lead to serious health problems for the fetus or newborn, including:
- Hemolytic anemia: The destruction of red blood cells at a faster rate than the body can replace them, leading to a dangerous lack of oxygen.
- Jaundice: A yellowing of the skin and eyes caused by a buildup of bilirubin, a byproduct of red blood cell breakdown.
- Brain damage: Severe jaundice can lead to kernicterus, a form of brain damage.
- Hydrops fetalis: Severe swelling in the fetus due to fluid buildup.
- Stillbirth or death: In the most severe cases, untreated Rh disease can be fatal.
Prevention with Rh immune globulin (RhoGAM)
Fortunately, due to modern medicine, Rh disease is almost entirely preventable. The primary treatment is an injection of Rh immune globulin (RhIg), commonly known as RhoGAM.
A typical schedule for RhIg injections includes:
- Around the 28th week of pregnancy.
- Within 72 hours of delivery if the baby is found to be Rh positive.
RhIg works by destroying any Rh positive fetal blood cells that have entered the pregnant person's bloodstream before their immune system can produce its own antibodies. This prevents sensitization from occurring. Injections may also be necessary after any event where blood mixing might happen, such as a miscarriage, ectopic pregnancy, abortion, or invasive prenatal testing like amniocentesis.
Comparison: Rh Negative vs. Rh Positive
| Feature | Rh Negative | Rh Positive |
|---|---|---|
| Individual Health | No effect on general health. | No effect on general health. |
| Pregnancy | Requires monitoring and potentially Rh immune globulin if fetus is Rh positive. | No specific Rh-related pregnancy risks. |
| Transfusions | Can only receive Rh negative blood. | Can receive both Rh positive and Rh negative blood. |
| Immune Response | Can produce antibodies against Rh positive blood. | Does not produce antibodies against Rh positive blood. |
What to do if you are Rh negative
For any Rh negative individual, the key is awareness. It is crucial to know your blood type and inform your healthcare providers. This is especially important for individuals who can become pregnant.
- Inform your doctor: If you are planning a pregnancy, inform your doctor of your Rh status. If you become pregnant, you will be tested during your first prenatal visit.
- Understand the treatment: Discuss the Rh immune globulin treatment plan with your doctor. This is a simple and highly effective preventative measure.
- Carry a blood type card: In an emergency, having your Rh status readily available can be life-saving for blood transfusions.
For more detailed information on managing an Rh incompatible pregnancy, consult a trusted medical resource like the American College of Obstetricians and Gynecologists.
