CMV and pregnancy: what is CMV, what are the potential risks of infection and how to reduce your risk

Cytomegalovirus (CMV) is a common viral illness, especially in young children. If someone is exposed to CMV in pregnancy, the virus can cross the placenta to the developing baby. This can (but won’t always) result in potential long term health problems/ disability for the infant.

Risks of unborn baby being exposed to CMV include
- Signs of congenital CMV at birth including small head, rash and problems with the liver, spleen and lungs
- longer term health issues such as vision and hearing loss, seizures, cerebral palsy and intellectual disability

About 1/200 babies are born with congenital CMV and about 1/5 of these have more significant or long term complications.

Generally, the risks are significantly higher if you are exposed for the first time in pregnancy and if you are exposed in the first half of pregnancy.
For this reason, I will often do a blood test to check for prior exposure, prior to/ early in pregnancy, in particular for those who work in healthcare or childcare or those with other children. This is in case there’s a known/ possible exposure to CMV in pregnancy so that we know what baseline results are and can interpret subsequent tests.

Risk is reduced through general measures to reduce your risk of exposure to body fluids of an infected person. This includes:
- careful hand washing after nappy changes and wiping of snotty noses (and possibly use of gloves, especially if occupational exposure)
- Avoid sharing food, drinks or toothbrushes with children
- Avoiding kissing your children on the lips, especially when they are unwell

If there is a known exposure in pregnancy, blood tests can be done for the mother/ parent and further tests can be done for the baby in pregnancy and after birth. If a baby has features of congenital CMV, early antiviral treatment has been shown to help, as well as regular monitoring and multidisciplinary support.

Resources:

CDC. CMV factsheet for pregnant women and parents. Available online here

NSW health. cytomegalovirus (CMV) and pregnancy factsheet
Available online here.