Rh factor and Rh-compatibility during pregnancy
The Rhesus factor or Rh factor is a protein that can be found on the surface of the red blood cells. If a person has this protein, he or she is Rh-positive, otherwise he or she is Rh-negative. 85% of the planet population are Rh-positive.
Rh factor and pregnancy
Rh compatibility is one of the tests performed when a women signs up at an Ob/Gyn clinic. The Rh factor can seriously affect the 9 months of pregnancy. If the baby inherits the father’s Rh factor while the mother is Rh-negative, the mother’s immune system considers the baby’s blood a foreign element and generates antibodies that attack the baby’s blood cells. A mismatch of Rh factors may cause anemia and other dangerous conditions in the baby, some of which could be fatal.
Blood type and Rh factor compatibility
Blood type can also be a reason for incompatibility. The four blood groups differ by the presence of specific proteins.
Blood type O (or “I”) has no specific proteins.
Blood type A (or “II”) contains protein A.
Blood type B (or “III”) contains protein B.
Blood type AB (or “IV”) contains both proteins.
The mother’s blood type O- may conflict with proteins A, B, and Rh factor.
The mothers blood type A- may conflict with protein B and Rh factor.
The mother’s blood type B- may conflict with protein A and Rh factor.
Blood type AB is compatible with all other blood types, except when the mother is Rh-negative and the father is Rh-positive.
|Blood type of the parents||Blood type of the baby (probability in %)|
|O + O||I (100%)||—||—||—|
|O + A||I (50%)||II (50%)||—||—|
|O + B||I (50%)||—||III (50%)||—|
|O + AB||—||II (50%)||III (50%)||—|
|A + A||I (25%)||II (75%)||—||—|
|A + B||I (25%)||II (25%)||III (25%)||IV (25%)|
|A + AB||—||II (50%)||III (25%)||IV (25%)|
|B + B||I (25%)||—||III (75%)||—|
|B + AB||—||II (25%)||III (50%)||IV (25%)|
|AB + AB||—||II (25%)||III (25%)||IV (50%)|
There is no conflict if the mother and the father have the same Rh factor. In this case the baby is Rh-compatible with the mother.
If the mother is Rh-positive, the father’s Rh factor is of no significance, even if the baby inherits the father’s Rh type. The baby’s blood will not contain any proteins unfamilliar to the mother’s immune system, so the pregnancy should have no complications.
Rh-negative blood does not cause any problems if the mother and the baby are both Rh-negative.
The problem arises when the baby is Rh-positive while the mother is Rh-negative.
The baby inherits the father’s Rh factor which is unfamiliar to the mother’s body. So the mother’s immune system starts generating antibodies that cross the placental barrier and attack the baby’s blood cells. The baby’s body tries to defend itself, its spleen and liver start working in overdrive and become enlarged. When the baby’s red cell count drops low enough, it suffers from anemia.
Consequences of Rh incompatibility
Rh-negative pregnant women should watch their health carefully and observe all doctor’s recommendations. This can prevent fetal edema, anemia, miscarriage or birth defects.
What to do if you have an Rh incompatibility
If you are Rh-negative while your husband is Rh-positive, this should be taken into account in planning your pregnancy. The Rh conflict often does not manifest itself during the first pregnancy, but in the second pregnancy its probability is very high because the mother’s blood most likely already has the Rh antibodies.
Rho(D) immune globulin
There’s a medicine called Rho(D) immune globulin that prevents the Rh conflict during pregnancy. So if you are Rh-negative while your husband is Rh-positive, you can still enjoy motherhood. But you will have to undergo regular blood tests during the pregnancy so the doctor could detect the onset of any Rh conflict on time.
In order to prevent Rh conflicts during subsequent pregnancies, Rh-negative women should be treated with Rho(D) immune globulin after live birth, abortion or miscarriage.
If you and your baby have different blood types and Rh factors, it does not necessarily mean health problems. In this day and age the immune system reaction can be successfully controlled by medications. An experienced doctor and your attention to your own body will help you carry a healthy child.