We talk to Dr Shazia Malik, Consultant Obstetrician and Gynaecologist at The Portland Hospital, about CMV and Hepatitis B in pregnancy
Cytomegalovirus (CMV), a member of the human herpesvirus family, is the most common viral cause of congenital infection, affecting 0.2–2.2 per cent of all live births. It is responsible for significant morbidity, especially in infants who are symptomatic soon after birth. It is the leading non-genetic cause of sensorineural hearing loss and a major cause of neurological disability. Around 10 to 15 per cent of neonates with congenital CMV will be symptomatic at birth, with a similar percentage developing problems later in childhood.
Being diagnosed with CMV infection when you are pregnant can be very stressful. However, it does not necessarily mean that your baby has the virus. Of all the women who catch CMV for the first time during pregnancy, only around a third will pass it to their unborn baby.
CMV is the most common infection passed from mother to unborn baby and occurs when a mother is infected with CMV and it passes through to her unborn baby. About one third of women who become infected with CMV for the first time during pregnancy pass the virus to their unborn babies. Around one in five children born with the virus will develop permanent problems due to the infection – nearly 1,000 babies every year. These problems include hearing loss, physical and motor impairment, seizures, autism, learning difficulties and visual impairment.
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.
The majority of babies born with congenital CMV will not have any symptoms at birth and will not suffer any long term problems. However, two or three babies are affected by the CMV virus every day in the UK – almost 1,000 babies every year. Congenital CMV causes more birth defects and childhood deaths than Down’s Syndrome, Toxoplasmosis (from cat poo) or Listeriosis (from soft cheese).
Can CMV be prevented?
The best way to try to avoid getting infected with CMV is by practicing good hygiene.
If you are pregnant, it is a good idea to:
- regularly and thoroughly wash your hands with soap and water, particularly when caring for children or handling anything with body fluids on it
- regularly clean surfaces and objects that may have body fluids on them
- wear gloves when changing nappies (not so practical!)
- avoid contact with children’s saliva
- avoid sharing food, cups, utensils, or toothbrushes
- this is especially important if you work with children in your day to day life
All pregnant women in the UK are offered a hepatitis B blood test when they first book for antenatal care.
If the mother is infected, her baby is given injections of antibodies and also immunised straight after birth (the transmission of the virus to the baby is thought to occur mainly during childbirth and not during the pregnancy).
With this treatment there is a good chance of preventing infection developing in the baby. Most obstetric units will manage your care in conjunction with a physician who specialises in the care of people with Hepatitis and other diseases which can affect the liver. It is important that your partner also gets tested, especially if this is a new and unexpected diagnosis. You will also be offered testing for Hepatitis C, which is another cause of chronic liver problems and needs specialist care and input.
Depending on when the infection is thought to have occurred – and how infectious it is at the time of diagnosis – you may need further blood tests and scans to monitor your liver and plan care for you during your pregnancy and for your baby after birth. If your baby has the course of vaccinations for Hepatitis B after birth, then you may be advised that it is safe to breastfeed.