When should Rh immune globulin be given postpartum?

• A. Immediately after birth is not necessary.
• B. Within 72 hours after birth to an Rh-negative mother with an Rh-positive baby.
• C. At 6 weeks postpartum.
• D. Only if the baby is Rh-negative.

Answer: (B)

Rh immune globulin postpartum is given to an Rh-negative mother after delivery to prevent sensitization to Rh-positive fetal red cells that may have entered the maternal circulation during birth. It works by neutralizing those fetal cells so the mother’s immune system doesn’t form anti-D antibodies, which could affect future pregnancies. It must be given within 72 hours after birth to be effective, and is indicated when the baby is Rh-positive. If the baby is Rh-negative, RhIG isn’t needed. Receiving it later (like at 6 weeks) is too late to prevent alloimmunization, and giving it only if the baby is Rh-negative is incorrect. The timing can be sooner rather than later, ideally as soon as possible after birth once fetal Rh status is known.