Diagnosis of CMV infection during pregnancy usually follows an abnormal scan or test. This can be confusing and stressful. However, it does not necessarily mean that the infection has been passed on to your baby or that they will be affected by the virus.
This section aims to explain how doctors diagnose CMV during pregnancy and where you can go for further support.
A saliva, urine or blood test can confirm whether the CMV virus is present (saliva and urine tests are the most reliable). Ideally, two samples should be collected. The sample must be taken within the first three weeks of your baby’s life to be sure that it is a congenital CMV infection, i.e. your baby caught it whilst in the womb. Otherwise they may have caught it during or after the birth, which won’t cause any long-term problems for full-term babies. Another reason for confirming the diagnosis within the first three weeks after birth is that treatment needs to begin within four weeks of life.
If your child tests positive for the CMV virus when they are more than three weeks old, it can be helpful to test the sample of blood that is collected from all babies in the UK when they are a few days old. This sample is called a Dried Blood Spot or Guthrie card and they are stored for around five years. This can help confirm whether it is a congenital infection.
Will all children born with congenital CMV have problems?
There is a huge range in the severity of problems that children with congenital CMV experience and many children will have absolutely no problems at all.
Most children born with congenital CMV will not show symptoms at birth. This is called ‘asymptomatic’ infection. Most of these children will not have any problems but around 15% of them will go on to develop hearing loss over time. Very rarely they may go on to have developmental or learning difficulties.
Some children will be born with obvious symptoms of congenital CMV such as a small head size (microcephaly), little red spots (petechiae), jaundice, enlarged liver and spleen, hearing loss or calcium deposits in the brain. Some of these children will go on to develop other problems such as cerebral palsy, seizures, ADHD, autism, developmental differences and learning delays or visual impairment.
Overall around one in every five children born with the virus will have permanent problems such as hearing loss or developmental disabilities due to the infection.
Will my child’s hearing loss get worse?
The most common disability associated with congenital CMV infection is hearing loss. It is progressive (worsens over time) for around half of children infected. Therefore, you need to have regular follow-ups with an Audiologist to monitor any changes.
If your child is diagnosed with congenital CMV before they are four weeks old then they can be treated with antiviral medication. This may help to stop hearing loss from getting worse.
What problems might emerge over time?
There isn’t a lot of evidence on this as most studies only track babies’ progress for a couple of years after diagnosis. One study followed children for five years and found that all moderate and serious problems were apparent in the first year of life. Milder problems (e.g. hearing loss in one ear, mild language delay, mild motor impairment that had limited implications for the child) were identified later on.
Families affected by CMV in the UK have a range of different experiences. Some have identified issues, for example around feeding, behaviour and sensory development that became more obvious as their child got older.
CMV Action can put you in touch with other families so you can hear about their individual experiences.
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