What are blood types?

Everybody has one of 4 blood types (A, B, AB or O). You inherit your blood group from your parents. These blood types are further identified as being either positive or negative. (For example, your blood type can be A positive or A negative). This shows your 'Rhesus factor' (RhD), which states if you have a protein known as 'D antigen' on the surface of your red blood cells.

What is haemolytic disease of the newborn?

Around 17 in every 100 people in Australia have a negative blood type. Being RhD negative isn’t usually a problem unless you are pregnant and your baby happens to be RhD positive. This can happen if the baby’s biological father is RhD positive.

Problems can occur if a small amount of your baby’s blood enters your bloodstream during pregnancy or birth. This may cause your body to make antibodies against the rhesus positive cells (known as ‘anti-D antibodies’). This is called a 'sensitising event'.

A ‘sensitising event’ can occur:

• during some tests you may have during your pregnancy (such as chorionic villus sampling (CVS) or amniocentesis)
• after miscarriage or termination
• after an injury or accident to your abdomen
• if your baby is in a breech position and you have an external cephalic version (where doctors turn the baby around inside the womb)
• during labour

A sensitising event usually doesn’t affect your first pregnancy. However, if you have another pregnancy with a rhesus positive baby, your immune response will be greater and you may make many more antibodies. These antibodies can cross the placenta and destroy your baby’s red blood cells. This may lead to a condition called 'rhesus disease', or 'haemolytic disease of the newborn', causing anaemia, jaundice and brain damage in the baby.

Can haemolytic disease of the newborn be prevented?

Rhesus disease is uncommon these days. It can usually be prevented with injections of a medicine called 'anti-D immunoglobulin'. You will be offered blood tests as part of your antenatal screening, so you will be told if your blood is RhD negative or positive.

You will be offered an injection at 28 and 34 weeks of pregnancy if your blood is rhesus negative. It may also be given at other times if there is concern about a sensitising event.

Currently, the only way to find out if a baby is RhD positive is after they are born and the umbilical blood can be tested. You can have the injection after your baby is born and tests show your baby is RhD positive, but doctors recommend that if you are RhD negative, you have it while you’re pregnant.

The anti-D injection is safe for both you and your baby. If you have already developed anti-D antibodies in a previous pregnancy you won’t need another injection in your next pregnancy. Your future pregnancies will be monitored more closely than usual, as will the baby after birth.

Can haemolytic disease of the newborn be treated?

If an unborn baby does develop rhesus disease, it can be treated. The recommended treatment will depend on how severely your baby is affected.

After birth, your baby will likely be admitted to a neonatal intensive care unit (a hospital unit that specialises in caring for newborn babies).

Treatment for rhesus disease after birth can include:

• light treatment (known as phototherapy)
• blood transfusions
• an injection of a solution of antibodies (intravenous immunoglobulin, also known as IVIG) to prevent red blood cells from being destroyed

If rhesus disease is not treated, severe cases can lead to stillbirth. In other cases, it could lead to brain damage, learning difficulties, deafness and blindness. However, treatment is usually effective and these problems are uncommon.