Info Centre - Chickenpox (varicella)

This NCT Information Sheet is about chickenpox and its effects on pregnant women and their babies. It is not intended to replace advice from a midwife or doctor and if you are at all concerned about your risk from chickenpox you should consult your midwife or doctor for further advice and information. This leaflet explains the potential risks from getting chickenpox if you have never had it, how you can catch the infection and what action your midwife or doctor will recommend. This leaflet has been written according to the most recent information available at the time of writing.

Summary

Most people in the UK have chickenpox as a child; so if you did, then you are probably immune. If you were born and lived outside the UK as a child, you may be less likely to have had chickenpox. If you are not sure whether you are immune or not, you can ask your doctor for a blood test. If you are not immune and you come into contact with chickenpox during your pregnancy then you or your baby could be at risk. The risk depends on which stage of your pregnancy you are at or if you have just given birth. You can have treatment that will help but you will need to see your doctor as soon as you know that you have been in contact with chickenpox, or if you develop a chickenpox rash.

What is chickenpox?

Chickenpox is an infectious disease caused by the virus Varicella zoster. It is also called Varicella by health professionals.

How do I know if I have got chickenpox?

The first thing you may notice is that you have a fever (raised temperature). You may have a runny nose, a cough or feel tired. Sometimes the first thing you may notice is a rash which usually comes a day or so after the runny nose and fever. The rash quickly turns into fluid-filled blister-type spots. They often start on the head and neck and then spread to the rest of the body. The rash can be very itchy.

How easy is it to catch chickenpox?

Chickenpox is very easy to catch. It is suggested that 15 minutes in a room with someone who has chickenpox or five minutes of face-to-face conversation may be enough to catch the virus and this is the definition used to predict how much risk you may have been exposed to. Someone with chickenpox is infectious from two days before the spots appear until the last of the spots has scabbed over and dried up, which may take up to five days. It takes between one and three weeks for someone to develop chickenpox after they have become infected. Chickenpox can be spread by coughing or sneezing, as the virus is in the fluid in the mouth and throat of an infected person. The liquid in the spots is also infectious until the scabs appear. For these reasons it is very easy to catch chickenpox.

Chickenpox and shingles – are they connected?

You can get shingles (herpes zoster) if you have had chickenpox. The chickenpox virus can stay in a person’s body for years after they have had chickenpox. Shingles is what happens when the chickenpox virus becomes activated again. With shingles you notice a rash of blisters in just one place on your body. Shingles blisters also have the chickenpox virus inside. So a person who has never had chickenpox can catch it from someone with shingles. However, this is very rare and is unlikely to happen if the blisters are covered over with clothing, bed clothes etc.

Are you immune?

A very small number of adults may still be at risk of catching chickenpox as 90% of adults raised in the UK are immune. If you were born and brought up outside the UK you may be less likely to have caught chickenpox. Some children can have chickenpox without being seriously ill and, when adults are tested, more of them are immune than can recall having chickenpox.

What effect does chickenpox have on a pregnant woman?

Chickenpox is much more serious in adults, especially pregnant women, because their hormone levels are altered and their immune system works differently. In extremely rare circumstances it can lead to death. Pregnant women appear to be at greatest risk late in the second or early in the third trimester. If you suspect you are infected or have been exposed to chickenpox, contact your midwife or doctor as soon as possible so that they can make arrangements for appropriate tests or treatment.

If you have chickenpox when you are due to give birth, you will be isolated by the hospital so you do not infect other mothers.

What effect does chickenpox have on the unborn child?

Although the placenta provides some protection against the virus there is around a 1% incidence of fetal varicella syndrome in the first twelve weeks of pregnancy and around a 2% incidence between 13 and 20 weeks. This can cause problems with limb growth, a very small brain, cataracts, growth retardation and skin scarring. A large number of babies who develop this syndrome are likely to die. Infection after 20 weeks does not appear to harm the baby. Infection in pregnancy is very rare.

What effect does chickenpox have on newborn babies?

If a mother has chickenpox seven days before she gives birth or within seven days after birth, her baby may get neonatal chickenpox. This can be serious for the baby. Babies who have chickenpox in the first seven days of life probably caught it when they were inside their mother.

When babies are exposed to chickenpox after they are born they may be slightly more at risk than older children but deaths are rare. In such cases the disease would begin between 7 and 28 days after birth. Breastfeeding will help protect the baby. If the mother is immune herself she will pass her antibodies to the baby. If she is not immune, she will probably catch the disease and share her antibodies with her baby through her breastmilk.

How does chickenpox affect breastfeeding mothers?

If a mother is already immune she cannot give chickenpox to her baby. If a mother is not immune and she gets the disease, her baby will be likely to catch chickenpox from her. If she is breastfeeding, her baby will receive help in fighting the infection through her antibodies in her milk.

Prevention

Two vaccines are available in the UK but the Joint Committee on Vaccination and Immunisation, which sets out the schedules for vaccines and the groups who should receive them, has recommended that these should only be used for non-immune healthcare workers who are in contact with at-risk members of the public, and close household contacts of immunosuppressed individuals. If you wish to have the vaccine you would have to be tested first to see if you are immune and then you would have to pay for a private course of vaccinations, as two doses are required. You would have to wait at least three months after the second dose before becoming pregnant. The vaccine is not normally provided under the NHS unless you are in one of the two identified groups of people.

If you are pregnant and know that you are not immune, avoid contact with anyone who may be infected. If you are pregnant and have been in contact with someone who has chickenpox, and you believe you may not be immune, visit your doctor as soon as possible. Your doctor can then arrange a blood test to see if you are immune, and if you are not, then you can be given varicella–zoster immunoglobulin (VZIG).

VZIG is made from blood donations from outside the UK, to reduce the risk of CJD. It is screened for a number of viruses and is also cleaned, but it still has a very small risk attached to using it, as with any other blood-derived product. It will not prevent chickenpox but will make the illness less serious, and it will only work for a short time.

VZIG needs to be given within 10 days of the mother coming into contact with chickenpox during the pregnancy but within 7 days if she develops chickenpox within 7 days before or after the birth. The baby will also need to be given VZIG if she is exposed to chickenpox in the first 7 days of life and she has no antibodies from her mother.

Treatment

Aciclovir is the drug that is used to treat chickenpox and reduce the severity of the disease. It must be started within 24 hours of the rash beginning. It is likely to be given to a baby who develops chickenpox despite having VZIG. Paracetamol can be used in the early stage to reduce a temperature and calamine lotion applied to the rash may help with itching. Contact your local pharmacist for further advice.

Remember – aspirin should not be given to anyone under the age of 16.

If you require further copies of this information sheet, or others in the series, you can obtain them from NCT Shop.

Further Support

The NCT holds a special experiences register to enable mothers to talk to other mothers who have had similar experiences. Contact the enquiry team on 0300 330 0770 or email enquiries@nct.org.uk.

References

Salisbury D, Ramsay M, Noakes K editors.

Immunisation against infectious disease. 3rd edition

London: Department of Health; 2006.

If you would like further copies of this information sheet (Code 1705), click here; other sheets in the series can be obtained from NCT Shop at www.nctshop.co.uk or on 0845 8100 100.

Page lasted updated 2008.