Guselkumab

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Date: September 2026, Version 1.0

Quick take

Guselkumab can be used in pregnancy if recommended by a specialist. Babies exposed after the first trimester might need to have some of their vaccinations later than usual.

What is it?

Guselkumab (Tremfya®) is an antibody treatment used to treat psoriasis, psoriatic arthritis, and inflammatory bowel disease. It works by reducing inflammation in the body.

Benefits

What are the benefits of using guselkumab in pregnancy?

Guselkumab can be a very effective treatment for pain and inflammation. Good symptom control can keep you well during pregnancy and help you to continue your usual daily activities.

Poorly controlled inflammatory conditions can increase the risk of some pregnancy complications. Treatment with guselkumab, when recommended by a specialist, may help reduce these risks.

Risks

What are the risks of using guselkumab in pregnancy?

Guselkumab does not cross the placenta during the first trimester, so it is unlikely to affect your baby’s early development.

Only a small number of pregnant women taking guselkumab have been studied. No safety concerns have been identified, but more research is needed to fully understand any risks.

When antibody treatments are used later in pregnancy, they can affect the baby’s immune system for a few months after birth. As a precaution, live vaccines are usually delayed until your baby is at least 6 months old. This mainly applies to the rotavirus vaccine and, in some cases, the BCG (tuberculosis) vaccine, if recommended. All other routine infant vaccines are not live and can be given as normal. Your healthcare team will advise you about your baby’s vaccinations.

Alternatives

Are there any alternatives to using guselkumab in pregnancy?

Possibly. Other medicines can be used to treat inflammatory conditions during pregnancy, although they may not work for everyone.

If guselkumab is controlling your symptoms effectively, your specialist may advise continuing it during pregnancy.

If you are planning a pregnancy, or become pregnant while taking guselkumab, you should discuss your treatment options with your specialist.

No treatment

What if I prefer not to take guselkumab during pregnancy?

Good treatment of inflammatory illness is important during pregnancy to maintain your quality of life and reduce the risk of complications for you and your baby.

Your doctor will be happy to discuss any concerns and help you decide what is best for you.

Will I or my baby need extra monitoring?

As part of routine antenatal care in the UK, women are invited for a detailed scan at around 20 weeks of pregnancy to check the baby’s development. No further scans to check for birth defects will be required, although extra growth scans are likely to be offered.

Are there any risks to my baby if the father has used guselkumab?

There is no evidence that guselkumab used by the father affects sperm or increases the risk of harm to the baby.

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 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.