Rhesus (Rh) Incompatibility During Pregnancy

By Medical Expert Team

Jun 05 , 2015 | 2 min read

“Marriages are made in heaven and celebrated on earth”. But there are times when you wonder if this is really true. Specially when a doctor tells you that your baby is going to have problem because you have a ‘blood group incompatibility'.

That brings us to the question – “what is blood group incompatibility?” , “Do all couples with different blood groups have a problem?' , ‘So is there a real problem? And what is the solution?'. I shall attempt to answer these questions in this article in a simple way.

When we talk of blood groups, we all know they are A, B, AB and O. Which may be either ‘Rh' positive or negative.

Rh negative and Rh positive refers to whether your blood has the ‘Rh' factor. The Rh factor is a glycoprotein on the red blood cells. If you have the glycoprotein on you are Rh positive and if you don't have it then you are Rh negative. Most people are Rh positive. This factor is inherited from your parents.

This Rh factor otherwise does not affect your general health but can cause problems in pregnancy. When the mother is Rh negative and the father is Rh positive, there is a 50% chance that the baby's blood group is Rh positive. That is where the problem begins.

During pregnancy & at the time of delivery of the first baby the mother is exposed to the Rh positive red blood cells from the baby's circulation which causes an immune reaction in the mother's body enabling her to produce antibodies to those foetal Rh positive cells. They do not cause any harm to the mother but these antibodies remain in the immune memory of the mother. In the subsequent Rh positive pregnancies these antibodies are reactivated and pass through the placenta into the baby's circulation causing damage to the baby's red blood cells.

The reaction may be mild to severe depending on how much antibody the mother's system produces and how much passes to the baby. In a mild reaction the baby may have anemia at birth and subsequently develop jaundice after birth.. The jaundice maybe mild, treatable with phototherapy or severe, requiring blood exchange transfusion in the baby.

In severe reactions the baby maybe affected before birth at any time in the gestation and may develop a condition called ‘Erythroblastosis fetalis' or ‘Hydrops fetalis' which may be a cause of intrauterine death of the baby.

But prevention is possible if the pregnancy is monitored carefully and after the birth of the first baby the mother is given an injection of Anti-D within 72 hours of the delivery.

Anti-D should be given during the pregnancy also to the Rh negative mothers to prevent minor immune reactions. Also has to be given in cases of any bleeding during pregnancy or abortions.

This anti-D masks the fetal red blood cells leaking into the mother's circulation thereby preventing the immune system activation of the mother which prevents the development of antibodies.

It is usually not the first pregnancy which is affected but subsequent pregnancies are at risk.

An Rh negative mother with an Rh positive father is potentially a high risk pregnancy and needs to be managed at a specialized center.

Written and Verified by:

Medical Expert Team