Zika virus

Date: February 2023, Version 8

Quick read

Zika virus can harm an unborn baby. Pregnant women should avoid travel to affected areas and unprotected sex with a partner who has recently travelled to such an area. If travel is essential, women should take strict measures to avoid mosquito bites.

What is it?

Zika virus is an infection which is mainly spread by mosquitos and can also be passed on through sex. In most cases, Zika virus causes no symptoms, and many people are not aware they have it. Zika can also cause mild flu-like symptoms, sore eyes and/or a rash. If caught in pregnancy, Zika virus can harm the unborn baby.

How might Zika virus affect an unborn baby?

Infection with Zika virus during pregnancy can stop the baby’s brain from forming and growing normally. As a result, the baby may be born with disabilities linked to altered brain development and may have a small head (microcephaly) and problems with hearing, learning and behaviour. Zika virus has also been linked to pregnancy loss. The highest risk of these problems is after having Zika infection in the first trimester.

How can I avoid catching Zika virus during pregnancy?

Pregnant women can avoid Zika virus by:

•    Avoiding travel to areas where there are high levels of Zika virus. 
•    Avoiding unprotected sex for the rest of the pregnancy with a partner who has recently had Zika virus or travelled to an area with Zika virus.

If travel to an area with Zika cannot be avoided, strict measures to avoid mosquito bites should be taken, including:

•    Using the insect repellent DEET on the skin. Other types of insect repellent are less effective and should not be used.
•    Staying inside as much as possible during mid-morning and from late afternoon to dusk. The mosquitoes that transmit Zika Virus are mainly active during daylight hours and most bites occur at these times.
•    Covering up exposed skin as much as possible with light-coloured, loose-fitting clothing.
•    Applying an insecticide that kills mosquitos on contact (such as permethrin) to clothing and mosquito nets.
•    Using mosquito screens on doors and windows.
•    Sleeping with mosquito nets over the bed.

All of these measures should be used together to minimise the risk of Zika virus.

For more information on avoiding mosquito bites, and use of insect repellents in pregnancy, please see the bump leaflets on malaria prophylaxis and insect repellents.

Where can I find more information about Zika virus and pregnancy?

The information about Zika virus and pregnancy is updated regularly. It is important to check the latest advice, particularly regarding high-risk areas. Useful websites include the Travel Health Pro website and the American CDC website. For more information on exposure to Zika virus in pregnancy there is a useful factsheet from the UK Health Security Agency.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information on insect repellents from www.uktis.org.

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.