Rhesus Factor and Pregnancy

The Rhesus factor also known as the Rh factor is a protein that can be found on the outside of red blood cells. If your blood cells have this protein, you are Rh positive. But if your blood cells do not have this protein, you are Rh negative. The protein is genetically inherited meaning it is passed from parent to child through genes. The fetus can inherit the Rh factor from either the father or the mother. If you did not inherit the protein, you are Rh-negative. Though majority of people are Rh-positive.

This protein does not affect your overall health, but it is important to know your Rh status if you are pregnant as Rh factor can cause complications during pregnancy especially if you are Rh-negative and your child is Rh-positive.

Rh sensitization normally is not a problem during the first pregnancy. Most issues occur in future pregnancies with another Rh positive baby. During that pregnancy, your antibodies cross the placenta to fight the Rh positive cells in your baby's body. As the antibodies destroy the cells, your baby gets sick. Your baby could have jaundice, heart failure, and enlarged organs.


Rhesus factor incompatibility

Each person has a blood type (O, A, B, or AB). Everyone also has an Rh factor which could either be positive or negative. A baby may have the blood type and Rh factor of either parent, or a combination of both parents.

Rhesus factor incompatibility occurs when a woman who is Rh-negative becomes pregnant with a baby with Rh-positive blood. A difference in blood type between a pregnant woman and her child causes Rh incompatibility.

During pregnancy, a mother’s blood does not usually mix with her baby’s blood but if the blood of an Rh-positive fetus gets into the bloodstream of an Rh-negative woman, her body will understand it is not her blood and will fight it by making anti-Rh antibodies (proteins in the blood produced in reaction to foreign substances, such as bacteria and viruses that cause infection). These antibodies can cross the placenta and try to destroy the blood of the fetus. This reaction can lead to serious health problems and even death in a fetus or newborn.

The Rh negative mom’s immune system sees the baby's Rh positive red blood cells as foreign. The immune system responds by making antibodies to fight and destroy these foreign cells. The immune system stores these antibodies in case these foreign cells come back again. This can happen in a future pregnancy.

Rh incompatibility can lead to a type of anemia (abnormally low levels of red blood cells in the bloodstream which in most cases are caused by iron deficiency) in the fetus in which red blood cells are destroyed faster than the body can replace them. Red blood cells carry oxygen to all parts of the body. Without enough red blood cells, the fetus will not get enough oxygen. In some cases, the fetus can die from anemia.

Facts about Rh factor

  • Rh disease occurs during pregnancy. It happens when the Rh factors in the mom’s and baby’s blood don’t match.
  • If the Rh negative mother has been sensitized to Rh positive blood, her immune system will make antibodies to attack her baby.
  • When the antibodies enter the baby's bloodstream, they will attack the red blood cells. This causes them to break down. This can lead to problems.
  • This condition can be prevented. Women who are Rh negative and haven’t been sensitized can receive medicine. This medicine can stop your antibodies from reacting to your baby’s Rh positive cells.

The symptoms of Rh disease may look like symptoms of other conditions. It is important you see your doctor for diagnosis.

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