This sheet is about exposure to clozapine in pregnancy and while breastfeeding. This information is based on available published literature. It 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 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 clozapine. Can it make it harder for me to get pregnant?
Studies have not been done to see 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 3 studies that looked at approximately 225 pregnancies exposed to clozapine does not suggest an increased chance of miscarriage.
Does taking clozapine 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. It is not known if clozapine can increase the chance of birth defects. 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 of birth defects.
There are case reports of infants with birth defects after exposure to clozapine in the first trimester. No pattern of birth defects was identified to suggest the birth defects noted were related to a single medication. There are also reports of babies without birth defects after prenatal exposure to clozapine.
Does taking clozapine in pregnancy increase the chance of other pregnancy-related problems?
It is not known if clozapine can increase the chance of 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 have suggested an increased chance for pregnant women 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. Some babies have also had unexplained seizures. There is one case report of a baby who had had a low white blood cell count. White blood cell count helps to see how a person’s immune system is working. If the immune system is not working well, a person could have a harder time fighting off infection. One case report cannot prove that the low white blood cell count was due to clozapine exposure in pregnancy.
Newborns exposed to clozapine during late pregnancy can 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 symptoms. Let your baby’s 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?
It is not known if clozapine can increase the chance of behavior or learning issues for the child. One study compared the development of infants exposed to clozapine during pregnancy to that of infants exposed to other antipsychotic medications and found some behavior delays at age 2 months and 6 months of age. However, the difference was not noticed by age 1 year.
Breastfeeding while taking clozapine:
Information about the use of clozapine during breastfeeding is very limited. Drowsiness (being sleepier than usual) was reported in 1 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 breastfed infants who did not have side effects. If you are breastfeeding while taking this medication, the infant should be closely watched for drowsiness and have their white blood cell count checked by a healthcare provider.
The product label for clozapine recommends that breastfeeding women not use this medication. However, the benefit of using clozapine and nursing may outweigh the possible risks to your baby. 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 your breastfeeding questions.
If a man takes clozapine, could it affect his fertility or increase the chance of birth defects?
There is a report of a man who was taking clozapine and had trouble with ejaculation, which could make it harder to get a woman pregnant. 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. 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/.
Please click here to view references.
