What is Rh factor?
The Rh factor is a protein attached to most people's red blood cells. Those people who have the Rh factor have blood types with a "+" at the end. People who don't have the Rh factor are in a minority, and their blood type will have a "-" at the end to indicate that they are Rh negative. Between one and 15 percent of most populations will be Rh negative the precise percentage differs by ethnicity and race, because the Rh factor is hereditary.
Those women who get pregnant and don't know their blood type yet will find out as part of their prenatal care. Moms to-be who are Rh negative, while the father of their baby is Rh positive, will face some special challenges during their pregnancy. If the baby's blood is Rh positive, there are potential dangers to the baby.
What do you need to know about being Rh negative and pregnancy?
Pregnant women who are Rh negative and pregnant with an Rh positive baby have the potential to develop antibodies to the baby's Rh positive blood. For this to occur, the baby's blood has to mix with the mother's blood or the mother has to have had an instance of Rh positive blood mixing with hers before. This is called Rh sensitization. It can happen during childbirth, miscarriage, abortion, amniocentesis, blood transfusion, or through other unknown means.
Just being pregnant with an Rh positive baby makes the process of sensitization quite likely. Those who are Rh negative and pregnant will be tested for Rh sensitization. Those who are not sensitized can receive an injection of Rh Immunoglobulin to prevent that from happening. This is usually sold as Rhogam, and administered during the 28th week of pregnancy and again right after the baby's birth. Shots of Rhogam are also recommended during other events in which sensitization can occur, like undergoing an amniocentesis for prenatal testing, or after an accident or ectopic pregnancy.
Women who had already developed antibodies to Rh positive blood when they became pregnant (probably during a previous pregnancy) are in a much more complicated situation. Historically, Rh disease in a baby was a major cause of miscarriage, stillbirth, and infant death. It can lead to jaundice, severe anemia, and brain damage as well. Thanks to Rhogam, Rh sensitization is much rarer now at least in countries where medical access and drug availability are not problems. If you are diagnosed with Rh sensitization during pregnancy by any chance, you and your baby will be monitored very carefully.
Doctors may recommend finding your baby's blood type out through amniocentesis (remember, your baby could be Rh negative as well, and in that case there would not be any worry about Rh disease). If your baby is Rh positive, blood tests and ultrasounds will keep an eye on the baby's health by watching out for severe anemia. These days, blood transfusions can be carried out while your baby is still in the womb! In some cases, depending on the gestational age, early delivery through cesarean will be preferable.