Cytomegalovirus (the large cell virus) is very common and about 50 per cent of the population of Britain have been infected with it at some time. Frequently the infection passes unnoticed or there may be mild ‘flu-like’ symptoms. The virus belongs to the Herpes family, which includes chicken pox, cold sore and glandular fever viruses. Once infection has taken place, the virus remains dormant within the body, usually with no ill effects. However, recurrences of the virus in body fluids may occur at intervals.

In the UK, about 40 per cent of women are susceptible to CMV at the time of pregnancy. The main risk is when women catch the viral infection for the first time in pregnancy. Women are usually only mildly unwell with a sore throat and flu-like illness. The chance of the unborn baby becoming infected is about 40 per cent. Over 90 per cent of infected babies have no signs of anything wrong at birth.


Medical text written November 1991 by Contact a Family. Approved November 1991 by Professor M Patton, Professor of Medical Genetics, St Georges Hospital Medical School, London, UK and Dr J E Wraith, Consultant Paediatrician, Royal Manchester Children’s Hospital, Manchester, UK. Last updated November 2011 by S Kadambari, Clinical Research Fellow and M Sharland, Consultant Paediatrician in Paediatric Infectious diseases, St George’s Hospital, London, UK.

What are the symptoms?

Some infected infants may go on to develop sensorineural hearing loss (SNHL), which is caused by damage to the pathway that allows sound in the inner ear to be interpreted by the brain, over the first five years of life. CMV is one of the main causes of bilateral (both ears) SNHL in childhood.

A small proportion of children infected with the virus during pregnancy or birth will be symptomatic, meaning that they display symptoms of CMV infection at birth and they can have pneumonia, liver disease, or neurological problems. The neurological problems associated with CMV infection include microcephaly, cerebral palsy, and developmental delay. Some, or all, of these symptoms may occur in individual cases.

How is it diagnosed?

CMV can be diagnosed during pregnancy by the presence of antibodies against the virus in blood and urine. CMV can be diagnosed in newborns by detecting the virus on urine or saliva samples taken within the first two weeks of life. Trials are currently looking at whether screening for CMV in the newborn is feasible.

How is it treated?

Trials are ongoing for the treatment of infected children in the newborn period with antiviral medication (medication that attacks the virus). There is no prenatal therapy at present, but trials are ongoing in this area too.

Inheritance patterns and prenatal diagnosis

Inheritance patterns

Prenatal diagnosis
Infections can be diagnosed in pregnancy, and women should be encouraged to seek medical advice for minor flu-like illnesses during pregnancy.

Is there support?

CMV Action

Freephone helpline: 0845 467 9590
Email: via website

The Organisation is a Registered Charity in England and Wales No. 1147633. It provides information and support to anyone affected by Congenital CMV, and can put families in touch with each other who may be facing similar issues or live nearby. 

Group details last updated May 2016.

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