What to expect from an anti-D injection for rhesus incompatibility

If your blood is rhesus negative and your baby may be rhesus positive, a small amount of the baby’s blood can enter your bloodstream during pregnancy or birth. Anti-D contains antibodies that clear these cells before your immune system learns to make its own long-lasting antibodies. It protects future pregnancies from rhesus-related complications; it does not change your blood group.

The injection is commonly given into a muscle, often the upper arm or thigh. Your maternity team decides when it is needed based on your blood tests, pregnancy stage and events such as bleeding, abdominal injury or an invasive procedure.

Tell your team if you have had anti-D before or reacted to a blood product. Report bleeding, a fall, a blow to your abdomen or a procedure during pregnancy promptly, because you may need assessment and anti-D within a particular clinical window. Keep your maternity records available and follow the appointment plan, including any blood tests.

Seek urgent maternity advice for heavy bleeding, severe abdominal pain, contractions, leaking fluid, reduced fetal movement or dizziness. After the injection, get emergency help for trouble breathing, swelling of the lips or face, widespread hives or collapse.

Ask what your blood group result means, whether your baby’s rhesus type is known, when anti-D is advised, and what to do after bleeding or an injury. Ask whether any observation or follow-up blood test is planned.