This sheet is about exposure to clozapine in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.
What is clozapine?
Clozapine is a medication that has been used to treat schizophrenia and schizoaffective disorders. Some brand names are Versacloz®, FazaClo®, and Clozaril®.
Sometimes when people 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 this 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 clozapine. Can it make it harder for me to get pregnant?
It is not known if clozapine can make it harder to get pregnant.
Does taking clozapine increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Information from three studies that looked at approximately 225 pregnancies exposed to clozapine does not suggest an increased chance for miscarriage.
Does taking clozapine increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. No large, controlled study has looked at this question, so it is not known if clozapine increases the chance for birth defects above the background risk. One reviewer combined studies and reported a birth defect rate of 4.5% out of 264 infants with first trimester exposure to clozapine. This is similar to the background risk for birth defects.
There are reports of infants with and without birth defects after exposure to clozapine in the first trimester. No pattern has been identified to suggest the birth defects seen were related to a single medication.
Does taking clozapine in pregnancy increase the chance of other pregnancy-related problems?
It is not known if clozapine can cause other 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 differences in birth weight or gestational age were reported in 187 children exposed to clozapine or another medication called olanzapine during pregnancy, when compared with an unexposed group.
Some studies suggest there may be an increased chance for a person who is pregnant to develop gestational diabetes when clozapine is used in pregnancy. Gestational diabetes can lead to babies that are bigger than expected (called large for gestational age). Be sure to talk with your healthcare provider about your chances of gestational diabetes. They can go over any screenings, tests, or treatments they recommend for you. For more information about gestational diabetes, see the MotherToBaby fact sheet here: https://mothertobaby.org/fact-sheets/diabetes-pregnancy/
I need to take clozapine throughout my entire pregnancy. Will it cause withdrawal symptoms in my baby after birth?
The use of clozapine during pregnancy can cause temporary symptoms in newborns soon after birth. These symptoms are sometimes referred to as withdrawal. It has been suggested that babies exposed to clozapine during late pregnancy be monitored for symptoms such as too much or too little muscle tone (stiff or floppy), sleepiness, agitation, problems with breathing and feeding, or unusual muscle movements (tremors). Not all babies exposed to clozapine will have these symptoms. It is important that your healthcare providers know you are taking clozapine so that if symptoms occur your baby can get the care that is best for them.
Does taking clozapine in pregnancy affect future behavior or learning for the child?
Based on the studies reviewed, it is not known if clozapine can cause behavior or learning issues for the child.
Breastfeeding while taking clozapine:
Information about the use of clozapine during breastfeeding is very limited. Drowsiness (being sleepier than usual) was reported in one infant exposed to clozapine in breastmilk. Another infant developed agranulocytosis (a life-threatening blood disorder when the body doesn’t make enough white blood cells). There are reports of breastfeeding infants who did not have side effects. If you are breastfeeding while taking this medication, the nursing child should be closely watched for drowsiness and have their white blood cell counts checked by a healthcare provider.
The product label for clozapine recommends that people who are breastfeeding not use this medication. However, the benefit of using clozapine may outweigh the possible risks. Your healthcare providers can talk with you about using clozapine and what treatment is best for you. Be sure to talk to your healthcare provider about all of your breastfeeding questions.
If a male takes clozapine, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
There is a report of a male who was taking clozapine and had trouble with ejaculation. This issue resolved when the medication was stopped. Studies have not been done in males to see if clozapine could increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
Please click here to view references.
National Pregnancy Registry for Psychiatric Medications: There is a pregnancy registry for women who take psychiatric medications, such as clozapine. For more information you can look at their website: https://womensmentalhealth.org/research/pregnancyregistry/atypicalantipsychotic/.
OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.
