This sheet is about exposure to mirtazapine in pregnancy and while breastfeeding. This information is based on research studies. It should not take the place of medical care and advice from your healthcare providers.
What is mirtazapine?
Mirtazapine is a medication that has been used to treat major depressive disorder and severe vomiting/nausea during pregnancy (hyperemesis gravidarum). A brand name for mirtazapine is Remeron®. MotherToBaby has fact sheets on depression https://mothertobaby.org/fact-sheets/depression-pregnancy/ and nausea and vomiting https://mothertobaby.org/fact-sheets/nausea-vomiting-pregnancy-nvp/.
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. Some people may have a return of their symptoms (relapse) if they stop this medication during pregnancy.
I take mirtazapine. Can it make it harder for me to get pregnant?
In some people, mirtazapine might raise the levels of a hormone called prolactin. High levels of prolactin can stop ovulation (part of the menstrual cycle when an ovary releases an egg). This would make it harder to get pregnant. Your healthcare provider can test your levels of prolactin if there is concern.
Does taking mirtazapine increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if mirtazapine could increase the chance of miscarriage. Depression itself might increase the chance for miscarriage.
Does taking mirtazapine 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 mirtazapine, might increase the chance of birth defects in a pregnancy. Studies and case reports have looked at nearly 5,000 pregnancies with mirtazapine exposure and have not found an increased chance of birth defects.
Does taking mirtazapine in pregnancy increase the chance of other pregnancy-related problems?
Some studies suggest that taking mirtazapine throughout pregnancy might 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). Research has also shown that when depression is left untreated during pregnancy, there could be an increased chance for pregnancy complications such as preterm delivery, low birth weight, and pre-eclampsia (high blood pressure and problems with organs, such as the kidneys) that can lead to seizures (called eclampsia). This makes it hard to know if it is a medication, an underlying condition, or other factors that are increasing the chance of these problems.
I need to take mirtazapine throughout my entire pregnancy. Will it cause withdrawal symptoms in my baby after birth?
The use of mirtazapine during pregnancy can cause temporary symptoms in newborns soon after birth. These symptoms are sometimes referred to as withdrawal. Symptoms might include sensitivity to light and sound (called excitability), fast heart rate, tremors, and problems regulating body temperature shortly after birth. In most cases, these symptoms are mild and go away on their own. Some babies may need to stay in a special care nursery until the symptoms go away. Not all babies exposed to mirtazapine will have these symptoms. It is important that your healthcare providers know you are taking mirtazapine so that if symptoms occur your baby can get the care that’s best for them.
Does taking mirtazapine in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if mirtazapine can cause behavior or learning issues for the child.
Breastfeeding while taking mirtazapine:
Mirtazapine passes into breast milk in small amounts. Most nursing babies have not had reported side effects from the medication in breast milk. If you suspect the baby has any symptoms (being overly sleepy) contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes mirtazapine, could it affect fertility or increase the chance of birth defects?
Studies have not been done to see if mirtazapine could affect a man’s fertility (ability to get a woman pregnant) 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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