Chickenpox in pregnancy: exposure, immunity and treatment

Chickenpox is caused by the varicella zoster virus and is usually a mild childhood illness. In pregnancy it can be dangerous for both the mother and the baby, as the NHS states. The RCOG explains that adults, and pregnant women especially, are at greater risk of pneumonia, hepatitis and encephalitis, with higher risk if you smoke, have lung disease, take steroids or are beyond 20 weeks.

The UKHSA guidance on viral rash in pregnancy lists chickenpox alongside parvovirus, measles and rubella as the rash illnesses where timely action can prevent or reduce harm. That guidance is aimed at professionals and was most recently updated in August 2024.

The RCOG describes how timing changes the picture. Up to 28 weeks there is a small chance of damage to the baby's eyes, limbs, brain, bladder or bowel, in fewer than 1 in 100 babies. Between 28 and 36 weeks the virus can stay quiet in the baby and come back later as shingles in childhood.

If a mother develops the rash in the final four weeks, about 1 in 4 babies will also develop chickenpox, and the illness can be severe if the baby is born within seven days of the mother's rash because there has not been time to pass on protective antibodies. The maternity and neonatal teams plan carefully in that situation.

The RCOG says roughly 9 out of 10 women in the UK are immune, usually because of childhood infection. A past history of chickenpox is a good guide, and testing is recommended if you are unsure, particularly for people brought up in tropical countries where infection in childhood is less common.

A blood test for varicella antibodies can usually be arranged quickly through your GP or maternity unit. The result decides whether any treatment is needed after a contact. Vaccination is not given during pregnancy, but non-immune women can be offered it after the baby is born, so it is worth asking.

The NHS tells pregnant women who have been near someone with chickenpox to get help from NHS 111 now, and the NHS pregnancy infections page urges you to speak to your GP, obstetrician or midwife immediately. Phone before attending so that others in the waiting room, who may be pregnant or have weakened immunity, are not exposed.

• Say whether the contact was face to face, in the same room for a period, or only brief.

• Say how many weeks pregnant you are and whether you have ever had chickenpox or the vaccine.

• If you are not immune, ask about varicella zoster immunoglobulin (VZIG).

• Avoid other pregnant women, newborns and anyone with a weakened immune system until the risk period has passed.

The RCOG describes VZIG as a blood product that strengthens the immune system for a short time. It can be given within 10 days of the exposure but is ineffective once the rash has started. It reduces the likelihood or severity of infection but does not always prevent it, so you should stay alert for symptoms.

Non-immune pregnant women are advised by the RCOG to avoid contact with other pregnant women for up to 4 weeks after exposure, because they may become infectious during that period even before developing symptoms.

Contact your GP or NHS 111 as soon as the rash appears, and tell them you are pregnant. The RCOG says antiviral tablets, aciclovir, should begin within 24 hours of the rash appearing and continue for a week. The NHS adds that antivirals for higher-risk people need to start within 24 hours of the spots appearing.

The NHS advises paracetamol for discomfort, plenty of fluids and cooling treatments, and says not to use ibuprofen unless a doctor tells you to because it may cause serious skin infections. Seek urgent help for breathlessness, chest pain, persistent vomiting, a rash that becomes infected or drowsiness.

The RCOG says shingles in pregnancy carries minimal risk to the baby, but you should stay away from pregnant women and newborns while the lesions are weeping. The NHS advises breastfeeding women with chickenpox symptoms to consult their GP, and newborns near anyone with chickenpox should be assessed promptly. If you are not immune, ask about vaccination before your next pregnancy.