Is clozapine safe 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 for 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. 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 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 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 have suggested 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. 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, that 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 increases the chance for 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.

If a male takes clozapine, could it affect fertility or increase the chance of birth defects?

There is a report of a male who was taking clozapine and had trouble with ejaculation, which could make it harder to get a partner 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 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/ .