This sheet talks about exposure to guselkumab in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is guselkumab?

Guselkumab is a medication used to treat adults with moderate to severe plaque psoriasis. It is taken by an injection under the skin. It is sold under the brand name Tremfya®.

I take guselkumab. Can it make it harder for me to get pregnant?

Studies have not been done to see if guselkumab could make it harder for a woman to get pregnant.

Should I stop taking guselkumab before or during pregnancy?

Talk with your healthcare providers before making any changes to this medication. They can go over your options, weighing the risks and benefits of treating or not treating your psoriasis. For more information about psoriasis in pregnancy, please see the MotherToBaby fact sheet on psoriasis in pregnancy at https://mothertobaby.org/fact-sheets/psoriasis-and-pregnancy/.

How long does guselkumab stay in my body?

People eliminate medications from their bodies at different rates. Guselkumab may remain in your body for up to three months after the last dose.

Does taking guselkumab increase the chance for miscarriage? 

Miscarriage can occur in any pregnancy. Studies have not been done to see if guselkumab increases the chance for miscarriage.

Does taking guselkumab increase the chance of having a baby with a birth defect?

In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. There are no human studies looking at exposure to guselkumab during pregnancy. Because guselkumab is an antibody, transfer of the medication to the baby may be low in early pregnancy, when many of the organs are forming.

Animal studies done by the manufacturer did not show an increase in birth defects with exposure to guselkumab.

Could guselkumab cause other pregnancy complications?

It is not known if guselkumab can cause pregnancy complications. There are no human studies looking at exposure to guselkumab during pregnancy.

Can I breastfeed my baby if I am taking guselkumab?

No information is available on the use of guselkumab during breastfeeding. Guselkumab is a very large protein, so not very much it is expected to pass into breast milk. Guselkumab is not well absorbed from the gut, so any medication that gets into breast milk would be unlikely to enter the baby’s system. Premature babies (born before 37 weeks of pregnancy) and newborns have digestive systems that are not fully developed, which could allow more of the medication to be absorbed from the breast milk. Be sure to talk to your health care provider about all of your breastfeeding questions.

What if the baby’s father takes guselkumab?

There are no studies looking at possible risks to a pregnancy when the father takes guselkumab. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/pdf/.

MotherToBaby is currently conducting a study looking at guselkumab and other medications used to treat psoriasis in pregnancy. If you are interested in taking part in this study, please call 1-877-311-8972 or or sign up at https://mothertobaby.org/join-study/.

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