Page ContentRh FactorFirst Trimester | Second Trimester | Third Trimester | Postpartum The Rh factor is an inherited protein that can be found on the surface of red blood cells. If your blood cells have this protein, you are Rh positive. If your blood cells don’t have this protein, you are Rh negative. During pregnancy, problems can occur if you are Rh negative and your baby is Rh positive (Rh incompatibility). If the blood of an Rh-positive baby gets into the bloodstream of an Rh-negative mother, her body will understand it’s not her blood and will fight it by making anti-Rh antibodies. These antibodies can cross the placenta and try to destroy the fetus's blood. This reaction can lead to serious health problems and even death in a fetus or newborn. During pregnancy, a woman and her baby usually do not share blood, but sometimes a small amount of blood from the baby can mix with the mother's blood. This can happen during labor and delivery. It can also occur with any of the following:Amniocentesis or Chorionic Villus Sampling-CVS (used to diagnose genetic problems) Bleeding during pregnancy Attempts before labor to manually turn a baby in the wrong position Trauma to the abdomen during pregnancy Miscarriage, ectopic pregnancy, or induced terminations. A simple blood test can determine your blood type, Rh status, and antibody status. If negative, your doctor will recommend an antibody, RhoGAM. This will help prevent your body from developing antibody against your baby's blood type. The typical circumstances in which Rhogam is given are the following:Routinely at 28 weeks of the pregnancy Within 72 hours after the birth of a Rh-positive baby A recent ectopic pregnancy, miscarriage, or termination Following an invasive procedure (amniocentesis, CVS, fetal blood sampling, or fetal surgery) Bleeding during pregnancy Trauma to the pregnancy (a fall, blow, or car accident) Attempts to manually reposition a baby in the wrong position for delivery Talk with your doctor if you have any questions about your blood type and how this will affect your pregnancy.