You might know what blood type you are, but do you know if you’re Rh positive or Rh negative? While this distinction might not seem meaningful to your everyday health, it’s important knowledge to have when trying to get pregnant. Positive and negative blood types are differentiated by the presence of the Rh factor on a red blood cell’s surface; most moms without the Rh protein are considered negative types. Because a baby’s health and development is watched carefully from the first trimester onward, expecting mothers submit themselves to a variety of tests and screenings to make sure there are no outstanding health issues for mom or baby.
What are the potential pregnancy complications associated with having a Rh negative blood type? The biggest concern stems from how a mom’s Rh negative blood type will react to carrying a fetus with a positive blood type. With genetics in mind, a fetus has about a 50 percent chance of having a negative or positive blood type and does not necessarily mirror the mother’s blood composition. So, if a mother is Rh negative but her fetus is shown to have a positive blood type, then the mother’s blood might form antibodies to attack the fetus’ Rh positive rich blood. Because the fetus is perceived as an infection by the antibodies, the developing baby is at risk for developmental harm or in some cases miscarriage.
To prevent sensitization from occurring during pregnancy (sensitization is the formal term for what happens when a mom’s antibodies try to attack her pregnancy) your doctor will perform a variety of actions to help prevent any damage to the fetus. You’ll undergo a blood test to see how you and your baby match up; if the difference in blood types suggests there might be issues, your doctor can order an antibody screening to monitor how your blood reacts. Sometimes your blood will not produce antibodies regardless if your baby is Rh-positive or not. You also might receive an Rh Immunoglobulin shot (RhIg) which will help protect against sensitization as well. These factors combined, along with careful fetal monitoring, should keep your pregnancy healthy through your last term.