The transfusion team at Bolton NHS Foundation Trust in the UK has introduced a new blood test for pregnant people with RhD negative blood type.

By looking at the free fetal DNA (ffDNA) in the maternal plasma, the new test can help determine the baby’s RhD status.

When a person with RhD negative blood type is pregnant with a baby that has an RhD positive blood group, problems can occur if the baby’s blood enters the mother’s bloodstream.

The mother may produce antibodies against the RhD positive cells, called anti-D antibodies, which then attack the red blood cells of the baby.

At 28 weeks, pregnant people with RhD negative blood type are currently given an anti-D injection to prevent the development of antibodies.

Another anti-D injection is also given after birth and if the baby has RhD positive blood type.

The new blood test will help RhD negative people avoid having the antenatal anti-D injection if their baby also has RhD negative blood type.

This will apply to nearly 40% of pregnant RhD negative people.

Bolton NHS Foundation Trust blood transfusion team principal clinical scientist Josephine McCullagh said: “We’re really pleased to now be able to offer this test to all RhD negative women at Bolton. It is a very accurate and non-invasive test and can reduce the need for anti-D injections.”

The new test helps to reduce unnecessary clinic attendances and injections during pregnancy.

It also helps conserve blood product stocks and reduce unnecessary anti-D injections, which comes with their own risks.