Chickenpox and pregnancy

Chickenpox is a very infectious illness caused by a virus called herpes zoster (part of the herpes family). The medical name for chickenpox is varicella. Most people in the UK get chickenpox in childhood, when it is usually a mild infection causing a rash. Once you have had chickenpox, you cannot catch it a second time, which means you are immune. This is because your body produces antibodies (the body’s defence system against infection) to prevent you getting it again.

Most pregnant women in the UK (9 out of 10) are immune to chickenpox. This is why it is uncommon in pregnancy, affecting only 3 in every 1000 pregnant women.

If you grew up in a tropical or subtropical area, you are less likely to have had chickenpox in childhood. If you subsequently move to the UK, you have a greater risk of catching chickenpox than women who were born and grew up in the UK. Your doctor or midwife may discuss testing your immunity while you are pregnant.

The symptoms of chickenpox take between 10 days and 3 weeks to appear. This is known as the incubation time – the time from when you catch it to when the symptoms start to show.

The first signs are fever and feeling unwell. This is followed by the formation of watery blisters that can appear anywhere over the body. The blisters itch. After a few days, the blisters burst, crust over and then heal. This may take up to 2 weeks.

If you are infected for the first time as an adult, it tends to be more serious.

Shingles is related to chickenpox but the symptoms are different. After you have had chickenpox, the virus stays in your body and can become active again later and this time it causes shingles. Shingles is a patch of itchy blisters on the skin that dry out and crust over in a few days. The affected area can be very painful.

You catch chickenpox from someone who currently has it. A person is contagious from two days before the rash appears to when all the blisters have crusted over.

During this time, you can catch chickenpox by being:

• in close contact with them
• face to face with them for at least 5 minutes
• in the same room with them for at least 15 minutes.

If you have not had chickenpox, you can be vaccinated against it. However, the vaccination can not be given in pregnancy. When you do have the vaccination, you should avoid getting pregnant for 3 months after the injection.

If you find out you are not immune to chickenpox during pregnancy, your doctor may discuss vaccination after the birth of your baby. You can still breastfeed if you have the vaccine at this time.

If you develop a rash after being vaccinated, you should avoid contact with women who have never had chickenpox and are either pregnant or trying to get pregnant.

If you have had chickenpox, you will be immune and there is nothing to worry about. You do not need to do anything.

If you have never had chickenpox, or are not sure, see your GP as soon as possible. You can have a blood test to find out if you are immune. 8 out of 10 women in this situation will be immune without realising it.

If you develop a rash in pregnancy, you should contact your GP or midwife.

If you are not immune to chickenpox and you come into contact with it during pregnancy, you may be given an injection of varicella zoster immune globulin (VZIG). This is a human blood product that strengthens the immune system for a short time, although it may not prevent chickenpox developing. It is safe to have in pregnancy.

VZIG can make the infection milder and not last for as long. The injection can be given within the first 10 days after you come into contact with chickenpox as long as you don’t yet have any symptoms. VZIG does not work once you have blisters.

What if I have had VZIG and come into contact with chickenpox again?

A second dose of VZIG should be given if you have come into contact with chickenpox again and it is 3 weeks or longer since your first injection.

Chickenpox can be serious for your health during pregnancy. Complications can occur such as chest infection (pneumonia), inflammation of the liver (hepatitis) and inflammation of the brain (encephalitis). Very rarely, women can die from complications.

You are at greater risk of complications if you catch chickenpox when you are pregnant if you:

• smoke cigarettes
• have a lung disease such as bronchitis or emphysema
• are taking steroids or have done so in the last 3 months
• are more than 20 weeks pregnant.

If any of these apply to you, you may need to be referred to hospital.

The risk of your baby catching chickenpox depends on when in your pregnancy you catch it. The highest risk is during the last 4 weeks of pregnancy.

If you catch chickenpox:

before 28 weeks of pregnancy

• There is no evidence that you are at an increased risk of early miscarriage. Your baby is unlikely to be affected; however there is a small chance that damage could occur to the eyes, legs, arms, brain, bladder or bowel. This only happens in fewer than 1 in 100 babies. You will be referred to a fetal medicine specialist for ultrasound scans and discussion about possible tests and their risks.

between 28 and 36 weeks of pregnancy

• The virus will stay in your baby’s body but will not cause any symptoms. The virus may become active again, causing shingles in the first few years of his or her life.

after 36 weeks of pregnancy

• This is the time when your baby is at greatest risk of getting chickenpox. If your baby is born within 7 days of your chickenpox rash appearing or you get chickenpox within the first week after birth, your baby may get severe chickenpox. He or she will be given VZIG and treated with an antiviral drug called aciclovir and monitored closely after birth.

It is safe to breastfeed if you have had chickenpox during pregnancy or after the birth of your baby. If you have blisters close to the nipple, you should express milk from that side (and throw it away) until they crust over.

If you catch chickenpox in pregnancy or when you are trying to become pregnant, you should avoid contact with other pregnant mothers and new babies until all your blisters have crusted over.

If you are more than 20 weeks pregnant, you can be given aciclovir to reduce fever and symptoms. This should be given within 24 hours of the chickenpox rash appearing. Aciclovir is not licensed in pregnancy but does not appear to be harmful for unborn babies and therefore may also be considered before 20 weeks. You will able to discuss the benefits and risks with your doctors.

Your GP should send you to hospital if you have chickenpox and develop any of the following:

• chest and breathing problems
• headache, drowsiness, vomiting or feeling sick
• vaginal bleeding
• a rash that is bleeding
• a severe rash.

These symptoms may be a sign that you are developing the complications of chickenpox. If this is the case, aciclovir may be given to you through a drip in your arm.

You should also be admitted to hospital if you have a condition that means your immune system does not work as well as it should (known as being immune suppressed).

If you need to be admitted to hospital, you will be nursed in a side room away from babies and pregnant women until your blisters crust over. This is normally 5 days after the onset of the rash.

The timing will depend on your own circumstances. It is best to wait until the chickenpox is over, to let you recover, so ideally at least 7 days from the onset of the rash. This will also give a chance for your immunity to pass to the baby. If you are very ill with chickenpox, particularly with any of the complications, your obstetrician will discuss whether you should have your baby early.

If your newborn baby has come into contact with chickenpox in the first 7 days of life and you are immune, your baby will be protected by your immunity and there is nothing to worry about.

If you are not immune, your baby may be given VZIG.

If you are immune to chickenpox, you do not need to worry. If you are not immune, the risk of getting chickenpox from someone with shingles on a covered part of the body is very small. If the shingles is widespread or exposed (such as the face or eye), there is a risk of chickenpox infection to you when the blisters are active and until they are crusted over. See your doctor for advice about treatment.

If you get shingles while you are pregnant, it is usually mild and there is no risk for you or your baby.