Most Nigerian couples today must have passed through some form of counselling at some point in time before marriage. The medical aspect of it always involves blood tests for genotype, blood group and assay for various infectious viruses. The level of awareness about the need for genotype compatibility has risen greatly in the past few years, however the tale of the Rhesus factor remains a story mostly untold despite the fact that it’s usually a result acquired alongside blood group tests.
Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you’re Rh positive. If your blood lacks the protein, you’re Rh negative. It is that simple. Rh positive is the most common blood type and having the Rh negative type neither predisposes anyone to any form of illness nor is an illness in itself. However, it can affect pregnancies, leading to miscarriages.
Usually, a baby can inherit the Rhesus factor from both parents. Maternal or paternal inheritance doesn’t matter if both parents are rhesus negative or rhesus positive. It also doesn’t really matter if the father is rhesus negative and the mother is rhesus positive. The problem comes when a baby inherits the type from a father who is rhesus positive while the mother is rhesus negative. What exactly is the problem here?
One of the ways the body reacts to foreign bodies is the production of antibodies against the ‘foreigner’ which help to destroy it. This is one way to understand the Rhesus factor incompatibility problem. A mother that lacks the rhesus antigen is rhesus negative and if she gets pregnant with a rhesus positive baby, what could happen? Antibodies could be formed in the mother against the fetus because her own body will recognize the rhesus antigen as foreign because she doesn’t have it. Antibodies are formed against the fetus’ blood cells in cases which the mother and fetus’ blood mix such as:
- Ectopic pregnancy — when a fertilized eggs implants somewhere outside the uterus, usually in a fallopian tube
- Bleeding during pregnancy
- Abdominal trauma during pregnancy
- The external manual rotation of a baby in a breech position.
It should also be understood that the antibodies formed during the first pregnancy of a rhesus positive baby do not usually affect the first pregnancy, since they’re just formed. The real problem comes in the event of another rhesus positive baby in the same rhesus negative mother. The antibodies cross the placenta, destroy the baby’s red blood cells leading to life threatening anemia that eventually culminates in death.
The first step in preventing the complications of rhesus incompatibility starts with identifying mothers at risk. Rh immune globulin is the injection given to women that have had exposure to the baby’s blood before the body would start to produce Rh antibodies. The immune globulin prevents the mother’s body from producing Rh antibodies during your pregnancy.