This sheet is about exposure to mepolizumab 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 providers.
What is mepolizumab?
Mepolizumab is a medication used with other medications to treat a severe type of asthma called eosinophilic asthma, and to treat eosinophilic granulomatosis with polyangiitis (Churg-Strauss Syndrome). A brand name of mepolizumab is Nucala®.
Mepolizumab belongs to a class of medications called monoclonal antibodies. Drugs in this class are very large proteins, and it is thought that they do not cross the placenta to the fetus very well in the 1st trimester; but likely do cross later in 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. Untreated or poorly controlled asthma during pregnancy increases the chance of complications for both the woman who is pregnant and the baby. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. For more information about asthma, please see the MotherToBaby fact sheet at: https://mothertobaby.org/fact-sheets/asthma-and-pregnancy/.
I take mepolizumab. Can it make it harder for me to get pregnant?
It is not known if mepolizumab can make it harder to get pregnant.
Does taking mepolizumab increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done to see if mepolizumab can increase the chance of miscarriage.
Does taking mepolizumab 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. We look at research studies to try to understand if an exposure, like mepolizumab, might increase the chance of birth defects in a pregnancy.
Studies have not been done in humans to see if mepolizumab increases the chance of birth defects. Studies in laboratory animals did not find an increased chance for birth defects. There are 3 published case reports of health pregnancies with mepolizumab use.
Does taking mepolizumab in pregnancy increase the chance of other pregnancy-related problems?
Studies have not been done to see if mepolizumab can increase the chance for pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). No adverse effects on fetal growth were seen when monkeys were given mepolizumab while pregnant.
Does taking mepolizumab in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if mepolizumab can increase the chance of behavior or learning issues for the child.
Breastfeeding while taking mepolizumab:
Mepolizumab has not been studied for use during breastfeeding. Mepolizumab is a very large protein, so it is thought to be unlikely that much of the medication would get into the breast milk. In addition, this medication is not well absorbed when taken orally, so if a baby swallowed small amounts in the milk, it would be unlikely to be absorbed. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes mepolizumab, could it affect his fertility or increase the chance of birth defects?
Studies have not been done to see if mepolizumab could affect male fertility (ability to make healthy sperm) or increase the chance of birth defects. In general, exposures that fathers or sperm donors 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/.
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