Does anti-D injection treat rhesus incompatibility?

Rhesus incompatibility can occur when a pregnant person has Rh-negative blood and the fetus may have Rh-positive blood. Small amounts of fetal blood can enter the pregnant person's bloodstream during pregnancy, birth, bleeding, abdominal injury, or some procedures. The immune system may then make anti-D antibodies. Anti-D contains prepared antibodies that clear Rh-positive cells before the immune system learns to react to them. It is preventive treatment, not a way to change either person's blood type.

If anti-D antibodies have already formed, an injection cannot undo that sensitisation. Care then focuses on monitoring the pregnancy and planning appropriate follow-up.

Your maternity team can check your blood group and antibody status and explain whether anti-D is recommended. Timing depends on the stage of pregnancy and whether a sensitising event has happened. Tell the team promptly about vaginal bleeding, a fall or blow to the abdomen, pregnancy loss, or an invasive procedure, even if you feel well. Keep any appointment arranged for anti-D and do not use a previous dose as a substitute for a new assessment.

Contact maternity care urgently after significant bleeding, abdominal trauma, reduced fetal movement, severe abdominal pain, or feeling faint. These symptoms need assessment for the pregnancy as well as consideration of anti-D. Seek emergency help for heavy bleeding, collapse, or severe pain.

Ask whether your blood test shows Rh-negative status or anti-D antibodies, when an injection is due, and what to do if bleeding or an injury occurs between appointments.