28 Weeks Pregnant
If you are Rh positive, or if both you and your partner are Rh negative, then you will not have a problem. If you are Rh negative (meaning you do not have the Rh factor) and your partner is Rh positive, there is a potential for complications. This is called Rh incompatibility.
The problem with Rh incompatibility is that if your baby is Rh positive, during delivery (or an abortion or miscarriage) some your baby's blood may mix with yours. Your body will react by forming antibodies which are formed to protect you. Therefore, Rh incompatibility is rarely a problem during a woman's first pregnancy because the mother has not been exposed to any Rh positive blood and therefore does not have any Rh antibodies.
However, after a mother has been exposed to Rh positive blood and developed antibodies, possible problems may occur in a future pregnancy. During another pregnancy, the antibodies that have been created can cross the placenta and attack the fetal red blood cells, causing anemia. This anemia can range from very mild to very serious.
To prevent this from happening in future pregnancies, healthcare providers give susceptible mothers who have no antibodies in their blood Rh-immune globulin around 28 weeks of pregnancy. The mother then receives another dose within 72 hours after her baby's delivery.
If you have developed Rh antibodies, the healthcare provider will likely recommend an amniocentesis to find out whether your baby is Rh positive or negative. If the baby is Rh positive, you will be watched very closely during your pregnancy for problems. In rare cases, early delivery or a blood transfusion may be necessary.