What are the effects of rubella during pregnancy?

Congenital rubella can have very serious implications for an unborn baby. The risks are increased during the early weeks of pregnancy and decrease as follows:

• Weeks 1-13: an 80% chance the baby will be infected
• Weeks 14-26: a 25% chance the baby will be infected
• Weeks 27-birth: between weeks 27 and 30 there is 35% chance the baby will be infected; after this time, there is a 100% chance the baby will be infected.

When the baby is infected has a significant influence on the extent of the damage done; the list below shows the likelihood of the baby having a birth defect when the mother develops rubella:

• Weeks 8-10: a 90% chance the baby will have a birth defect
• Weeks 11-16: a 10-20% chance the baby will have a birth defect
• Weeks 16-20: birth defects are very rare during this time; however there have been cases of deafness caused by rubella.
• Weeks 20-birth: there is very little chance of the baby having a birth defect during this stage of the pregnancy.

Rubella is most dangerous when the mother is infected during the first trimester of the pregnancy; if this is the case, the following problems may occur:

• Cataracts and visual problems
• Deafness
• Heart problems
• Delayed development
• Swollen wounds in the lungs, liver, bone marrow and brain
• Smaller than average head (this is because the brain does not develop fully)

Rubella can also cause miscarriage, premature birth and stillbirth.

In later life, babies born with congenital rubella syndrome may also develop further serious health problems, including:

• Pneumonitis (a viral illness which causes the lungs to become swollen)
• Diabetes mellitus: this causes the levels of glucose in the blood to be too high
• Thyroid problems, including hypothyroidism (underactive thyroid gland) and hyperthyroidism (overactive thyroid gland)
• Panencephalitis: this is a progressive condition that causes the brain to swell and subsequently causes problems with mobility and mental functions.