In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to mirtazapine may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is mirtazapine?

Mirtazapine is a medication used in the treatment of major depressive disorders. The brand name for mirtazapine is Remeron®.

I would like to stop taking mirtazapine before becoming pregnant. How long does the medication stay in my body?

You should not make any changes in your medication without first talking to your health care providers. While everyone breaks down medication at a different rate, on average it takes between five and ten days for most of the mirtazapine to be gone from the body after taking the last dose. Stopping antidepressant treatment can increase the chance for depression to return or become worse.

Can taking mirtazapine make it harder for me to get pregnant?

Mirtazapine can cause an increase in the hormone prolactin. Higher levels of prolactin in women might cause difficulty getting pregnant. If you are having difficulty getting pregnant, speak with your health care provider and they may choose to test your prolactin level.

I am currently taking mirtazapine and I am already pregnant. Should I stop taking it?

You should not stop taking any medication without first talking with your health care provider. Studies have shown that when depression is left untreated during pregnancy, there is an increased chance for miscarriage, preeclampsia (dangerously high blood pressure), preterm delivery, low birth weight and a number of other harmful effects on the mother and the baby. Please see our fact sheet on Depression and Pregnancy at https://mothertobaby.wpengine.com/fact-sheets/depression-pregnancy/pdf/.

The benefits of taking mirtazapine for your specific situation and the potential risks to the baby should be considered before a decision is made. If you and your health care provider decide together that stopping mirtazapine is right for you, you should gradually decrease the dose over a period of time to avoid withdrawal symptoms.

Can taking mirtazapine during my pregnancy cause birth defects or have other harmful effects?

Studies and case reports have looked at nearly 1000 pregnancies where the woman was using mirtazapine and have not found an increased chance for birth defects in her baby.

A possible association with mirtazapine use in pregnancy and a small increased chance for miscarriage and preterm birth has been raised, but additional studies are needed to confirm these findings. Some studies suggest that the depression itself rather than the mirtazapine is increasing the chances for these pregnancy complications.

Will taking mirtazapine have any long-term effect on my baby’s behavior and development?

There are no studies looking at whether taking mirtazapine during pregnancy causes changes in the baby’s behavior and intellect. Long-term studies are needed to determine this, but it is reassuring that studies on other antidepressants have not found large changes in behavior and development in children exposed to these medications during pregnancy.

I need to take mirtazapine throughout my entire pregnancy. Will it cause withdrawal symptoms in my baby at birth?

There have been a few reports of babies that are very sensitive to stimulation such as light and sound (called excitability), rapid heart rate, tremors and problems regulating their temperature shortly after birth when their mothers used mirtazapine during pregnancy. These newborn complications are similar to what has been seen with other types of antidepressants. In most cases, signs of neonatal withdrawal are mild and go away on their own, but some babies may need to stay in a special care nursery until the symptoms go away. You should inform your obstetrician and your baby’s pediatrician that you are taking mirtazapine so that any extra care can be readily provided.

Can I take mirtazapine while breastfeeding?

Most case reports have found that mirtazapine enters milk in low amounts, and that nursing babies do not have any side effects from the medication. Studies are needed to confirm these findings and to determine if there are any long term effects from exposure through breastfeeding. Make sure your baby is growing well, and not overly sleepy from the small amount of mirtazapine in milk. If you have any concerns, speak with your baby’s doctor.

The father of my baby was using mirtazapine when we got pregnant. Should I be concerned?

There are no studies looking at paternal use of mirtazapine prior to or at the time of conception. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at https://mothertobaby.wpengine.com/fact-sheets/paternal-exposures-pregnancy/pdf/.

References Available Upon Request.