Montelukast

(Date: April 2020. Version: 3)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by the UK Health Security Agency (UKHSA) on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is it?

Montelukast (Singulair®) is prescribed for people with asthma, usually when symptoms are not fully controlled with inhalers.

Is it safe to use montelukast in pregnancy?

When deciding whether to use montelukast during pregnancy it is important to weigh up the potential benefits to your health and wellbeing against any possible risks to you or your baby, some of which may depend on how many weeks pregnant you are.

Uncontrolled or poorly controlled asthma in pregnancy has been linked to a number of adverse outcomes including stillbirth, preterm birth, low birth weight in the baby, and preeclampsia in the mother. Good control of asthma in pregnancy is therefore vital. Your doctor or specialist will be able to help you make decisions about your treatment.

What if I have already taken montelukast during pregnancy?

If you are taking any medicines while pregnant, you can discuss this with your doctor. You can then decide together whether ongoing treatment is appropriate, and if so, your doctor will ensure that you are taking the most effective dose.

Can using montelukast in pregnancy cause my baby to be born with birth defects?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

Studies that include at least 1,000 pregnant women do not raise concern that exposure to montelukast in early pregnancy is linked to birth defects in the baby. However, ongoing research is ideally required to confirm this.

Can taking montelukast in pregnancy cause miscarriage?

Two small studies found no link between miscarriage and use of montelukast in early pregnancy. However, as only around 250 women were studied in total, more research is required to confirm this finding.

Can taking montelukast in pregnancy cause stillbirth?

No studies have investigated the likelihood of stillbirth following exposure to montelukast in pregnancy.

Can taking montelukast in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

A single study found that women who used montelukast during pregnancy may be more likely to have a preterm birth and therefore a baby with a low birth weight (preterm babies tend to be smaller). However, these pregnancy outcomes have been linked to asthma itself. Further research is therefore required to determine whether use of montelukast can directly cause preterm birth and related low infant birth weight, or whether these effects are linked to asthma in the mother.

Can taking montelukast in pregnancy cause learning and behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

No studies have assessed the learning and behaviour of children exposed in the womb to montelukast.

Will my baby need extra monitoring during pregnancy?

Most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects as part of their routine antenatal care. Taking montelukast in pregnancy is not expected to cause problems that would require extra monitoring of your baby.

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

No studies have specifically investigated whether montelukast used by the father can harm the baby through effects on the sperm, however most experts agree that this is very unlikely. More research on the effects of medicine use in men around the time of conception is needed.

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.

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General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

   

www.medicinesinpregnancy.org

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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