|MadSci Network: Anatomy|
Dear Donna, When speaking of blood type, most people are referring to whether their blood is A, B, AB, or O. Any combination of these blood types can produce a healthy baby. A problem can potentially arise, however, if a mother's blood cells are Rh negative and a father's are Rh positive. The Rh factor is a molecule on red blood cells. If a person's blood is Rh negative, they do not have this molecule on their blood cells. So, if a pregnant woman has Rh negative blood and the father of her baby has Rh positive blood, there is a chance the baby will also have Rh positive blood. During birth (or miscarriage or abortion) this Rh negative mother can be exposed to the blood of her Rh positive baby, due to the traumatic nature of the birthing process. If some of this baby's blood enters the bloodstream of the mother, the mother's immune system will detect the Rh factor on the baby's blood cells and will begin to attack these cells with antibodies. The first time the mother is exposed to the Rh factor, there is usually no harm done because the mother's immune system will not have time to make enough antibodies to harm the baby. But, if this woman becomes pregnant again, her immune system is armed with millions of antibodies against the Rh factor, and if her baby is Rh positive the baby can be harmed. This harm can range from jaundice and slight anemia to the death of the baby. This condition sounds very serious, but it is, in fact, very easy to prevent. On a pregnant woman's first prenatal visit her blood is tested. If her blood is Rh negative she will be given two injections that will prevent any harm to her baby. One of the injections will be given when she is 28 weeks pregnant and another shortly after the birth of her child. This is one reason why it is important to visit a doctor as soon as you suspect you may be pregnant. Thank you very much for your question. Sincerely, Sarah Martin Mason Reference: Tabsh, Khalil and Nancy Theroux. Essentials of Obstetrics and Gynecology. Saunders. 1992. pp.305-6.
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