Rh Negative Blood Type and Pregnancy

Generally, pregnancy is a happy occasion in a woman's life. But for some, pregnancy may also lead to serious complications. The human blood is divided into 4 groups, A, B, AB and O. Each blood group is further classified as Rh negative and Rh positive. Whether a person is Rh negative or positive, is determined by the presence of 'D' antigen in the blood.

If 'D' antigen is present, the person is said to be Rh positive and those lacking it are called Rh negative. So, when a Rh negative person is exposed to Rh positive blood, their bodies will start producing an antibodies. These antibodies act against the Rh positive blood and protect the body from these intruding blood cells.

This is good in some cases, but Rh negative blood type and pregnancy can lead to a serious complication for the pregnant mother.

When a Rh negative woman conceives a baby with a Rh positive man, there are chances the fetus will either have Rh positive blood group or Rh negative blood group. One cannot know the blood group of the unborn child, until after birth.

Problems arise when the mother is Rh negative and the baby is Rh positive. Remember, positive is dominant over negative. Thus, it may have problems during the course of pregnancy.

Problems will arise only when the Rh positive blood from the unborn child finds it way into the system of Rh negative mother. This may happen during the pregnancy or during childbirth. When this happens, the mother's body will start producing antigens against the Rh positive fetal blood.

If the blood is mixed during the pregnancy, the antigens will start attacking the fetus by crossing the placental barrier. This will lead to severe anemia (called haemolytic disease or haemolytic anemia) in the fetus as the red blood cells will be destroyed by the antigens.

In serious cases, it may lead to fetal death and a miscarriage. Suppose the blood gets mixed during the labor, any future pregnancies are at risk, due to the presence of antigens in the blood. If second pregnancy also results in Rh positive fetus, the antibodies will take no time to cross the placenta and attack the fetal blood.

There are little risks involved with the first pregnancy and Rh negative blood. This is because it is very rare for fetal blood to mix with the mother's blood during pregnancy. It is generally during labor, when the mother's blood is sensitized by Rhesus positive blood.

However, women who have had a previous miscarriage, or medical termination before their first pregnancy are at risk of developing complications. Also, women who have had an amniocentesis, or chorionic villus sampling (CVS), are at risk of developing Rh negative blood type and pregnancy complication.

The Rh antigens produced against the Rh positive fetal blood, will attack the baby. The blood cells decrease in number and cause swelling in the unborn baby's abdomen. This leads to serious developmental problems and fetal death. When this occurs, it is called 'erythroblastalis fetalis'.

The advancement in medical science has bought good news for Rh negative mothers. The Rhesus negative blood type and pregnancy complications can be easily prevented. Women who are not yet sensitized to the Rh positive blood are given Rh immunoglobulin (RhIg). This is a blood product that is given in form of an injection.

This immunoglobulin helps 'minimizing' the reaction of the Rh antigen against the Rh positive blood cells. This injection is given around the 28th week of pregnancy. When the baby is born and found to be Rh positive, the mother is given another dose of RhIg injection.

This prevents the mother's body from making more antigens against the Rh positive red blood cells that may have entered her body during or before the delivery.

RhIg injections are to be administered for every pregnancy. After every child born Rh positive, the mother has to be given a RhIg injection. These injections should be given even after a Rh negative woman suffers a miscarriage, ectopic pregnancy or medical termination of pregnancy to reduce the risk of antibodies formation against a future Rh positive fetus.

Every woman trying to get pregnant should get her and her partners blood tested. This will help her know their Rh status and prevent pregnancy complications due to Rh negative blood type.