This sheet is about exposure to guselkumab in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider.
What is guselkumab?
Guselkumab is a medication that has been used to treat moderate to severe plaque psoriasis and psoriatic arthritis in adults. It is given by injection under the skin and is sold under the brand name Tremfya®. For more information about psoriasis, please see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/psoriasis-and-pregnancy/.
Sometimes when women find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.
I take guselkumab. Can it make it harder for me to get pregnant?
It is not known if guselkumab can make it harder to get pregnant.
Does taking guselkumab increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if guselkumab can increase the chance of miscarriage.
Does taking guselkumab increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. In studies including more than 200 pregnancies exposed to guselkumab, there has not been a reported increase of birth defects. In manufacturer follow-up data on 178 exposed pregnancies, no birth defects were reported.
Very little guselkumab is expected to cross the placenta and reach the developing pregnancy during the first trimester (when many of the fetal organs and body structures are forming). More of the medication can cross the placenta starting in the second trimester.
Does taking guselkumab in pregnancy increase the chance of other pregnancy-related problems?
Available studies have not found an increased chance of stillbirth or preterm delivery (birth before 37 weeks of pregnancy) with guselkumab use during pregnancy. Studies have not been done to see if guselkumab can increase the chance of other pregnancy-related problems such as low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does taking guselkumab in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if guselkumab can increase the chance of behavior or learning issues for the child.
Breastfeeding while taking guselkumab:
Guselkumab is a large protein, and little of the medication is expected to pass into breast milk. Guselkumab is not well absorbed from the intestines (gut) when swallowed, so any medication that would get into breast milk is unlikely to enter the baby’s bloodstream. If you suspect the baby has any symptoms (such as fever or frequent infections), contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes guselkumab, could it affect his fertility or increase the chance of birth defects?
In clinical trial data, 12 pregnancies were reported in partners of men taking guselkumab. No increased chance of birth defects or other pregnancy complications has been reported with paternal use of guselkumab. Studies have not been done to see if guselkumab could affect men’s fertility (ability to make healthy sperm). In general, exposures that men have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
MotherToBaby is currently conducting a study looking at guselkumab and other medications used to treat psoriasis, ulcerative colitis, and Crohn’s disease 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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