Rhesus Factor during Pregnancy

Apart from the classification of blood based on ABO system, in which the blood is that of type A, B, AB or O, it can also classified based on the rhesus factor. That is represented by the plus or minus sign after the type is mentioned. That is how we have an A – or a B + blood group. In pregnancy, the positive or negative sign has special significance. If you are rhesus negative and so is your partner, it is alright. In case you are rhesus negative but your partner isn’t, your baby would have a blood group incompatible with yours, and this will lead to problems.

Importance of rhesus factor in pregnancy

If Rh- blood is in contact with Rh+, the resultant reaction would kill the Rh + cells. This type of reaction is similar to the one which gets rid of viruses of cold and flu in your blood. In both these reactions, the blood develops antibodies to the substance that is deemed foreign to the blood. Moreover, these antibodies, whether to the Rh+ cells or to the viruses of colds and flu, do not leave the blood ever.

The trouble with this is that during pregnancy, the placenta can give in from the uterine wall allowing the baby’s blood to mingle with that of the mother’s bloodstream. This is never a problem for women if not for the rhesus factor. If the baby has Rh + blood while the mother is Rh –, and the baby’s blood goes into mother’s bloodstream, there will be trouble. The mother’s body will treat the baby’s blood cells as foreign substance and develop antibodies against them.

However, this does not lead to problems in the first pregnancy, as the mixing of the bay’s blood with that of his mother is usually not a lot. But if she goes on to have a second child, the antibodies that she developed during the first pregnancy can enter the baby’s bloodstream and destroy the Rh + red blood cells.

How the problem is tackled

This lack of compatibility between the mother’s blood and that of the baby can be worrisome but there is a way out. There is treatment available to counteract the problems that might result from incompatible blood.

An injection of Rh antibodies is given to a mother who has the Rh negative blood, within a few hours of her delivering a baby that has Rh positive blood. This gets rid of Rh positive blood cells transferred to her from her baby. This prevents the formation of antibodies that harms the babies that may come next.

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