Mirtazapine

Date: March 2025, Version 4.0

Quick take

Mirtazapine can be used in pregnancy if recommended by a GP or specialist.

What is it?

Mirtazapine is mainly used to treat depression.

Benefits

What are the benefits of taking mirtazapine in pregnancy?

Mirtazapine can improve the symptoms of depression. Its use can help you remain well during pregnancy and while looking after your baby.

Risks

Are there any risks of taking mirtazapine during pregnancy?

There is no evidence that mirtazapine affects the baby’s development or increases the chance of miscarriage or stillbirth.

If you take mirtazapine in later pregnancy, you will usually be advised to have a hospital delivery. This is because:

• Mirtazapine and similar medicines can sometimes cause short-term withdrawal symptoms in the newborn baby. Observation of your baby for a few days after birth may be needed.

• Rarely, use of similar drugs to mirtazapine in late pregnancy can cause a problem in the baby, where blood flow to the lungs is too high; this is called persistent pulmonary hypertension of the newborn (PPHN). After birth, your baby will be checked for breathing problems by a midwife or paediatrician.

Alternatives

Are there any alternatives to taking mirtazapine in pregnancy?

Possibly. Your GP or mental health specialist will be able to advise whether mirtazapine is still the best treatment during pregnancy.

No treatment

What if I prefer not to take medicines during pregnancy?

Mirtazapine use may be recommended in pregnancy to prevent relapse of depression and give you the best chance of staying well. If you are advised to continue mirtazapine in pregnancy, you can discuss the risks and benefits with your doctor.

Will my baby need extra monitoring?

Women in the UK will be offered a very detailed scan at around 20 weeks of pregnancy as part of their routine antenatal care. Taking mirtazapine in pregnancy would not normally require extra monitoring for birth defects.

If you have taken mirtazapine around the time of delivery, your baby may require extra monitoring after birth because of the possible risk of neonatal withdrawal.

Are there any risks to my baby if the father has taken mirtazapine?

We do not expect any increased risk to your baby if the father takes mirtazapine.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.