Blood incompatibility

What is blood incompatibility?

When a mother and baby have different blood types (groups). Antibodies (special proteins in the blood steam) from the mother enter the baby's blood during pregnancy. This can lead to baby's red blood cells being broken down more quickly than usual and may lead to jaundice and anaemia in baby.

Why does this occur?

There are two ways in which mothers and babies blood may not match:

  • ABO Incompatibility

    Most common and generally milder. Most often develops in newborns whose mothers are blood type 0 and who have a baby with a different blood type such as/either A, B, or AB.

  • Rhesus (Rh) Incompatibility

    Differences between a specific protein (on a blood type) called the Rh factor. The most common factors are D, C, c, E and e. Other less common antigens include Kell, Duffy and many others. Rhesus disease develops when a mother is Rh negative and has a Rh positive baby.

What are the signs of blood incompatibility?

In some (most severe) cases the incompatibility may have been detected before baby was born. These babies are managed by the Maternal-Fetal Medicine team.

For most (less severe) cases of incompatibility the signs occur after birth. At first there may be an excess build up of bilirubin in baby's blood leading to jaundice (yellow colouring of the skin). In some cases the baby develops anaemia (low red blood cells). Signs of anaemia in babies include pale colour, tiredness, poor feeding and fast breathing.

How is blood incompatibility treated?

Most treatments are given on the postnatal ward. Phototherapy (special blue light) may be required to treat jaundice. If the jaundice is very high your baby may need supplemental feeds, or admission to NICU for IV fluids.

Anaemia is checked with regular blood tests and in some cases a blood transfusion(s) is/are necessary.

What is the blood tested for?

Bilirubin (jaundice) and red cell count (called haemoglobin or Hb). Sometimes reticulocytes - a sign that your baby is actively making red blood cells.

Who organises the blood tests after we go home?

Before discharge the hospital paediatrician makes a plan for the first blood test to be done in the community. A blood request form will be given for parents to take baby to their local Labtest clinic. In some cases the midwife or neonatal homecare nurse will arrange for the blood test to be collected from your home.

How do I get the results?

The result is reviewed by a doctor and your midwife or neonatal homecare nurse. You will be notified of the blood test result by phone and any treatment required. In most cases all that is needed is to organise the date for the next test.