Why get tested?
To determine the ABO and RhD blood group, and any possible blood group antibodies (commonly referred to as red cell antibodies), that may affect pregnancy and cause haemolytic disease of the newborn (HDN). HDN occurs when red cell antibodies present in the mother’s bloodstream cross the placenta and destroy the unborn baby’s red cells. This may lead to serious complications such as severe anaemia, brain damage and sometimes death of the baby. Early identification and detection helps maternity carers to support a pregnancy plan tailored for safe care and management of both the mother and the baby.

When to get tested?
As part of the routine antenatal care provided by a midwife or doctor. The first blood test is normally taken during the first trimester (12-16 weeks), with any subsequent blood tests as directed by the lead maternity carer.

If a woman is RhD negative, she may require an injection of anti-D (also known as Rh (D) immunoglobulin) during pregnancy and/or after delivery. Her lead maternity carer will advise if, and when, these injections are required. If anti-D is required, the blood sample for the 28 week antibody screen must be taken before the injection is given.

Sample required?
A blood sample drawn from a vein in the arm.

Frequency of testing?
This depends on results from the first antenatal tests. If the woman is RhD negative, a further antibody screen will be taken at 28 weeks. If a blood group antibody is identified, frequent blood tests may be required during the pregnancy.