Dr Renuka Sekar explains Rhesus disease

Dr Renuka Sekar is the clinical lead for maternal fetal medicine at RBWH

Did you know there are technically four main blood groups? A, B, AB, O and then we have positive and negative variations known as the Rhesus (Rh) systems.

A person’s Rhesus type is determined by a pair of genes, each one inherited from one parent.

Blood is either Rh-positive or Rh-negative, depending on whether the inherited protein is present or absent.

According to Dr Renuka Sekar, the clinical lead for maternal fetal medicine at the Royal Brisbane and Women’s Hospital, around 85% of the population are Rh-positive, and 15% of the population are Rh-negative.

But what happens when a pregnant mother has Rhesus negative blood and the baby in utero has Rhesus positive blood?

“Rhesus disease is a condition where antibodies in a pregnant woman’s blood attack her baby’s blood cells, and if left untreated it can cause the baby to become anaemic and develop newborn jaundice,” Dr Sekar said.

“We now have the ability to test the fetal blood type from 12 weeks like a NIPT test, using the mother’s blood.”

If the mother is Rh-negative, with negative antibodies, and the baby is positive, they will be offered Anti-D immunoglobin to avoid forming antibodies.

In some mothers, due to the high risk of the baby being anaemic, their babies will require blood transfusions in utero which can happen every 3-4 weeks depending on the weight and age of the baby.

“Fortunately, since the introduction of these transfusions, means the baby can spend longer in utero and be delivered at an appropriate gestation,” Dr Sekar said.