Anti-D in pregnancy: what to know

RhD is a marker found on some red blood cells. If a pregnant person does not have the marker but the fetus does, fetal cells entering the pregnant person's bloodstream can trigger an immune response called sensitisation. This can create antibodies that cross the placenta in a future pregnancy and affect RhD-positive fetal red blood cells. Anti-D injection provides antibodies that clear exposed cells before that response becomes established.

Blood-group and antibody testing helps the maternity team decide whether anti-D is suitable. It may be discussed at a planned point in pregnancy and after birth, or after bleeding, abdominal injury, pregnancy loss, or a procedure that could allow blood to mix.

Attend blood tests and maternity appointments, and tell the team promptly about bleeding, a fall, abdominal impact, or a procedure. Include when the event happened and whether you have received anti-D before. The timing of treatment depends on the situation, so contact the service rather than waiting for the next routine visit. Keep the injection record with your pregnancy notes and share it with future maternity clinicians.

Call your maternity unit urgently for heavy bleeding, severe abdominal or one-sided pain, fainting, fever, or reduced fetal movement. Emergency help is needed for severe breathing difficulty, swelling of the face or throat, or collapse after an injection. Anti-D helps with sensitisation risk but does not diagnose the cause of bleeding or pain.

Ask whether your blood group and antibody screen make anti-D appropriate, when it should be given, what happens if bleeding occurs again, and how the treatment will appear in your records. Ask which number to call at night or on a weekend.