Rhesus incompatibility in pregnancy

Overview

Rhesus disease is the name given to incompatibility of the rhesus factor in the mother's and baby's blood types. The child's red blood cells are destroyed by the mother's antibodies (haemolysis, haemolytic disease of the foetus and newborn), which can threaten the baby's life. Pregnancy check-ups and tests to determine the blood types of the mother and child are therefore important.

Symptoms

Before the birth

• Anaemia (foetal anaemia)
• Hydrops fetalis (foetal hydrops): fluid is accumulated in the baby's tissue and body cavities
  • Life-threatening condition (among others, risk of heart failure)
  • Most common cause of foetal death owing to rhesus incompatibility
• Result of anaemia: enlarged spleen and liver (hepatosplenomegaly)

After the birth

• Lack of oxygen (hypoxia)
• Anaemia in the newborn (neonatal anaemia)
• Newborn jaundice (neonatal jaundice)
  • Placenta no longer helps to remove metabolic waste products
  • Kernicterus (build-up of bilirubin in the brain) can be life-threatening

Complications

Thanks to anti-D prophylaxis (see below), complications caused by rhesus incompatibility in pregnancy occur very seldom in the developed world today. If the prophylaxis is not administered, the above symptoms can occur.

Causes and treatment

Cause

Blood type incompatibility

• ABO incompatibility
  • Usually barely noticeable to mild symptoms
  • Approx. 1 out of 100 pregnancies
  • Can already occur during the first pregnancy
• Incompatibility in rhesus system
  • Usually involves rhesus factor (RhD)
  • Hereditary; RhD can be either positive or negative
  • Approx. 15% of the population is rhesus negative (RhD negative)

Rhesus incompatibility

• Rhesus-negative mother must have been exposed to foreign RhD positive blood
• Sensitisation to the RhD antigen (on the surface of the foreign blood cells)
• The immune system forms anti-D antibodies (against the RhD positive blood)
• This is why the child of a first pregnancy is usually not affected
• At birth: mixing of blood between the mother and the newborn
  • Rhesus-negative mothers therefore form anti-D antibodies when pregnant with a rhesus-positive child
  • During a rhesus-negative mother's second pregnancy with a rhesus-positive child, these antibodies destroy the child's red blood cells (haemolysis)

Risk factors for sensitisation of a rhesus-negative woman

• Previous miscarriage or abortion
• Previous pregnancy with a rhesus-positive child
• Blood transfusions
• Bleeding during pregnancy
• Ectopic pregnancy
• Gynaecological procedures

Further treatment by your doctor / in hospital

Possible tests

• Blood test for mother (blood type, search for antibodies)
• Determination of child’s blood type (can be derived from mother's blood)
• Ultrasound of the umbilical blood vessels (Doppler ultrasound)
• Blood count of newborn
  • Signs of destruction of red blood cells (haemolysis)
  • Accumulation of antibodies

Possible therapies

• Transfusion of blood into the unborn child's umbilical vein (only in hospital)
• Iron and red blood cell supplements
• Phototherapy for newborn (light therapy)
• Rhesus prophylaxis for rhesus-negative women
  • Routine anti-D prophylaxis for mothers in weeks 28 to 30 of the pregnancy and after the birth
  • After invasive procedures, bleeding during pregnancy
  • After a miscarriage, ectopic pregnancy or abortion

What can I do myself?

• Attend routine pregnancy check-ups (preventive examinations)

When to see a doctor?

• At the beginning of pregnancy for obstetric support
  • Blood type and rhesus system are recorded
  • Test to search for antibodies (if rhesus is negative)
• Generally for all preventive examinations during pregnancy

Further information

Swiss Society of Paediatrics (Schweizerische Gesellschaft für Pädiatrie)
www.swiss-paediatrics.org

Schweizerischer Hebammenverband (Swiss Federation of Midwives)
www.hebamme.ch

Synonyms

rhesus incompatibility in pregnancy, rhesus incompatibility, pregnancy complications, blood type, blood group, rhesus, rhesus disease, haemolytic disease of the newborn, rhesus incompatibility (pregnancy complication), erythroblastosis fetalis, haemolytic disease of the foetus and newborn