Chickenpox in pregnancy: risks, what to do and treatment
In brief
Chickenpox in pregnancy (varicella-zoster virus infection) is uncommon, because most pregnant women are protected, having had it as children. In a woman who is not immune, the infection can cause pneumonia in the mother, harm the foetus mainly between 13 and 20 weeks of amenorrhoea (about 2% of cases), and cause severe chickenpox in the newborn if it occurs around the time of birth. After contact, call your doctor or midwife promptly, without going straight to a waiting room.
Why is chickenpox a concern during pregnancy?
Chickenpox is caused by the varicella-zoster virus (VZV). Mild in children, it is more severe in adults and particularly in pregnant women. The virus can also cross the placenta. French guidelines were updated in 2024 by the French-language Society of Infectious Diseases (SPILF), endorsed by the French College of Gynaecologists and Obstetricians (CNGOF) and perinatal societies.
Having had chickenpox as a child usually gives lifelong protection. If you are not sure whether you have had it, a blood test (serology) can check your immunity, ideally before pregnancy. This is one of the topics covered at the first pregnancy appointment and throughout your care up to giving birth in Paris.
The virus spreads through the air and through contact with the blisters. An infected person is contagious from about two days before the spots appear until all the lesions have crusted over. Symptoms appear 10 to 21 days after contact.
What are the risks of chickenpox at each stage of pregnancy?
The risks for the baby depend mainly on how far along the pregnancy is when the mother is infected. The table is based on a prospective study of 1,739 pregnancies in Germany and the United Kingdom.
| Timing of the mother's chickenpox | Main risk for the baby |
|---|---|
| Before 13 weeks of amenorrhoea | Rare congenital varicella: about 0.4% |
| Between 13 and 20 weeks | Highest risk of congenital varicella: about 2% |
| After 20 weeks | No congenital varicella observed; possible shingles in early childhood |
| From 5 days before to 2 days after birth | Potentially severe neonatal chickenpox, because the baby has not yet received the mother's antibodies |
Congenital varicella syndrome combines skin scarring and abnormalities of the limbs, eyes and brain. It is rare but serious, which is why careful ultrasound monitoring is needed.
Shingles during pregnancy (reactivation of the virus in a woman who has already had chickenpox) carries no proven risk for the baby: in the same study, no harm to the foetus was seen after shingles in the mother.
For the mother
The main complication is varicella pneumonia, which is more common in pregnant women and in smokers. It causes a cough, breathlessness and a high fever, usually a few days after the rash, and can be serious. Encephalitis and hepatitis are rarer.
What should I do if I have been in contact with chickenpox while pregnant?
Significant contact means, for example, living in the same household, or spending more than a few minutes face to face or in the same room as someone who has chickenpox or uncovered shingles.
- If you have had chickenpox or have been vaccinated (two doses), you are normally protected. Still tell your doctor if you have any doubt.
- If you have not had it or do not know, call your gynaecologist, your midwife or the maternity unit promptly. Do not go straight to a waiting room, so as not to expose other pregnant women.
- An urgent blood test checks your immunity. In the vast majority of cases, it shows that you are protected.
- If you are not immune, preventive treatment may be offered, depending on the time since contact and your situation: an oral antiviral or, in some cases, specific immunoglobulins. The decision must be made quickly, ideally within days of exposure.
Without immunity, you are considered potentially contagious from day 8 to day 21 after contact. During this time, avoid other pregnant women, newborn babies and people with weakened immune systems.
How is chickenpox treated during pregnancy?
- Antiviral treatment (aciclovir or valaciclovir) as soon as possible, preferably within 24 hours of the rash starting. It shortens symptoms and lowers the risk of complications in the mother. These medicines have a long safety record in pregnancy.
- Hospital admission if there are breathing symptoms, persistent fever, a very widespread or bleeding rash, neurological signs, or risk factors (smoking, lung disease, weakened immune system). Treatment is then given intravenously.
- Simple measures: paracetamol for fever, short nails, local care of the spots. Anti-inflammatory drugs (ibuprofen, pain-relief doses of aspirin) must not be taken: see our article on medicines during pregnancy.
- Isolation until all the spots have crusted over.
Monitoring the baby
If chickenpox occurs before about 20 to 24 weeks, repeated ultrasound scans look for signs of harm to the foetus. A consultation at a prenatal diagnosis centre is offered. Amniocentesis may be considered if the scan shows an abnormality.
Chickenpox close to birth
When possible and safe for the mother, the team may suggest delaying the birth by a few days, to give the mother's antibodies time to pass to the baby. The exposed newborn is monitored and given appropriate preventive treatment. Breastfeeding is normally still possible; the team will explain how.
When should I go to the maternity unit urgently with chickenpox?
If you have chickenpox, or have been exposed without being immune, seek urgent care (calling the maternity unit ahead so you can avoid the waiting room) if you have:
- a cough, breathlessness, chest pain, bloodstained phlegm: in France, call 15 (SAMU) or 112, or your local emergency number;
- a high fever that persists or comes back;
- a very widespread rash, or spots that bleed or turn black;
- severe headache, drowsiness, confusion, problems with balance;
- contractions, bleeding, leaking fluid;
- reduced baby movements.
A rash in the days before or after birth must be reported to the team immediately.
How can I prevent chickenpox during pregnancy?
- Before pregnancy: if you have not had chickenpox, a blood test is offered. If you are not immune, vaccination (two doses) is recommended for women of childbearing age. Effective contraception is needed for 1 month after each dose.
- During pregnancy: the vaccine is contraindicated, because it is a live attenuated vaccine. Accidental vaccination in very early pregnancy has not shown any particular risk and is not a reason to end the pregnancy; talk to your doctor. See our article on vaccines during pregnancy.
- After the birth: vaccination is possible, including while breastfeeding.
- In everyday life, if you are not immune: avoid contact with people who have chickenpox or shingles, and let your older children's nursery or school know you are pregnant in case of an outbreak.
If you are not sure whether you have had chickenpox, mention it at the pre-conception consultation at the practice: a blood test can be prescribed to check your immunity.
Frequently asked questions
I had chickenpox as a child: am I protected during pregnancy?
Yes, in the vast majority of cases, past chickenpox gives lifelong protection. Catching it a second time is exceptional; if in doubt, a blood test can confirm your immunity.
Is a relative's shingles dangerous for my pregnancy?
Shingles is less contagious than chickenpox, because the virus only spreads through contact with the lesions. If you are not immune and have been in contact with uncovered shingles, tell your doctor as you would for chickenpox.
My child has chickenpox and I am pregnant: what should I do?
If you have had chickenpox or are vaccinated, you are normally not at risk. If not, contact your doctor promptly for a blood test and, if needed, preventive treatment.
Can chickenpox cause a miscarriage?
Available data do not show a clear increase in miscarriage risk after chickenpox in the first trimester. The main risk for the baby is congenital varicella, especially between 13 and 20 weeks.
References
- Vauzelle C, et al. Varicella vaccination, pregnancy and breastfeeding: The current situation. Gynecol Obstet Fertil Senol, 2024. doi:10.1016/j.gofs.2024.01.012 — PMID 38309510
- Charlier C, et al. Recommendations for clinical practice: prevention and management of varicella zoster virus (VZV) infection during pregnancy and the perinatal period (extended version). Gynecol Obstet Fertil Senol, 2025. doi:10.1016/j.gofs.2025.01.001 — PMID 39805558
- Enders G, et al. Consequences of varicella and herpes zoster in pregnancy: prospective study of 1739 cases. Lancet, 1994. doi:10.1016/s0140-6736(94)92943-2 — PMID 7802767
Dr Olivier KadochObstetrician-gynaecologist and gynaecological surgeon in Paris (16th and 5th arrondissements). Former chef de clinique-assistant (senior registrar) at the Paris public hospitals (AP-HP); individually accredited by the French National Authority for Health (HAS). RPPS 10003957809. Background and practice locations
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