During a mother's first pregnancy, Rh incompatibility typically does not pose a health concern. This is because fetal blood usually does not enter the mother's circulatory system during gestation. However, exposure can occur during childbirth when maternal and fetal blood may mix. If this happens, the mother's immune system may recognize the Rh protein as foreign and begin producing antibodies. It's important to note that Rh-negative pregnant women can also be exposed to Rh-positive blood, potentially leading to antibody production, through other circumstances such as blood transfusions, miscarriage, ectopic pregnancy, abdominal trauma during pregnancy, bleeding during pregnancy, or invasive prenatal procedures like amniocentesis and chorionic villus sampling.