Administering Rh negative globulin, also known as Rh immunoglobulin (RhIg), is a critical intervention in obstetric care. It is necessary when the mother is Rh negative and the fetus is Rh positive. This situation poses a risk because if fetal Rh positive blood cells enter the maternal circulation, the mother’s immune system may produce antibodies against the Rh factor. This process is known as sensitization.
If a Rh negative mother becomes sensitized to Rh positive blood, it can lead to hemolytic disease of the newborn (HDN) in subsequent pregnancies. This condition can cause severe anemia, jaundice, and other serious health issues for the newborn. Administering RhIg during pregnancy and after delivery of a Rh positive infant can prevent the mother's immune response, thus protecting both her and future pregnancies.
The other scenarios presented do not necessitate the administration of RhIg, as they do not involve the critical immunological conflict between an Rh negative mother and an Rh positive fetus.