Bad Blood - The Rh Factor

Blood testing is a routine part of most prenatal care. Early in her pregnancy, a mother will have blood drawn to test for any number of possible complications or conditions. One of the simplest of these tests can also be the most important - blood typing and factor screening.

Along with our blood type, each of us also has an Rh factor which is either positive or negative. The majority of people are Rh positive and this factor will never affect them during their life. The one time that Rh factor can become a serious issue, however, is during pregnancy.

The problem arises when an Rh negative mother and an Rh positive father produce a baby which is also Rh positive. If the baby’s blood crosses into the mother’s system, her body can become "sensitized" and react as if it were under attack, creating antibodies which will fight against the Rh positive baby. If this happens, the antibodies can cause the baby’s red blood cells to break down and anemia to develop. In the most severe cases this can lead to illness, brain damage and even death.

If a mother has not become sensitized, hemolytic disease can be prevented with injections of Rh immunoglobulin, which suppresses the mother's reaction to Rh positive cells. Usually sensitizing will occur early in the pregnancy, but there are rare occasions when a mother won’t develop problems until later. In these women, Rhlg injections can be given at about 27 weeks gestation to prevent complications later in the pregnancy.

Many babies with hemolytic disease are born without incident, but some have serious complications and may require early delivery. In either case, the baby’s blood will need to be carefully screened throughout the pregnancy and the mother will usually be given an Rhlg injection within 72 hours of birth. Babies with serious complications can be given blood transfusions before and after birth to help reduce risk.

As with any serious medical issue, the key is early detection and treatment. If you have any concerns about you or your baby’s Rh factor, be sure to discuss them with your doctor or midwife. Being well informed is the best way to assure yourself of a healthy pregnancy and a happy result.