How effective is anti-D injection for rhesus incompatibility?

Rhesus incompatibility can occur when an Rh-negative pregnant person carries an Rh-positive baby. A small amount of the baby's blood may enter the pregnant person's circulation during pregnancy, bleeding, an injury, a procedure, or birth. The injection contains anti-D antibodies that clear Rh-positive blood cells before the immune system learns to make its own antibodies.

This protection is aimed at preventing sensitisation. It does not change the baby's blood group and does not treat antibodies that have already formed. Testing during pregnancy helps the maternity team decide whether anti-D is needed and when it should be offered.

Attend the appointments where your blood group and antibody screen are reviewed. Tell your maternity team promptly about vaginal bleeding, abdominal injury, an invasive procedure, or any event that could cause blood mixing, even if you feel well. Anti-D is time-sensitive after some events, so do not wait for the next routine visit to report them.

Keep a record of any injection you receive and ask whether another dose is needed later in pregnancy or after birth. The team may assess the baby's blood group after delivery and arrange post-birth protection when appropriate.

Contact your maternity service urgently for bleeding, significant abdominal pain, a blow to the abdomen, reduced fetal movement, or fluid loss. These symptoms need assessment for pregnancy complications as well as a decision about anti-D. Seek emergency help for heavy bleeding, fainting, severe pain, or feeling suddenly very unwell.

Ask whether you are Rh-negative, whether antibodies were found on your blood test, and which pregnancy events should prompt anti-D. You can also ask when routine doses are planned, what to do if bleeding happens outside clinic hours, and whether protection is needed after birth.