(Date: February 2018. Version: 2)

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?

Varenicline is a medicine which is used to reduce nicotine cravings in order to stop smoking.

There is strong evidence that smoking during pregnancy increases the risk of miscarriage, some birth defects, premature birth, low birth weight, and certain pregnancy complications. Pregnant women and women trying to conceive should therefore avoid smoking. Studies have shown that stopping smoking before week 20 of pregnancy can reduce the risk of having a low birth weight baby. 

If you need help to stop smoking during pregnancy please speak to your doctor or midwife. Please read the bumps information leaflet on smoking if you would like to find out more about the risks of smoking during pregnancy.

Is it safe to use varenicline in pregnancy?

There is very little information on the safety of varenicline in pregnancy. Its use in pregnancy is therefore not generally recommended. Advice can be obtained from a pharmacist or your health professional about the other options, such as nicotine replacement therapy, that are available to help you to stop smoking in pregnancy. For more information see the Bump leaflet on use of nicotine replacement therapy in pregnancy.

What if I have already taken varenicline during pregnancy?

It is always a good idea to let your doctor know that you are pregnant if you have taken any medicines in case you need any additional monitoring or treatment.

This leaflet summarises the scientific studies relating to the effects of varenicline on a baby in the womb. 

Can use of varenicline 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.

Two small studies of a total of 343 women who took varenicline in very early pregnancy provide no proof of a link with birth defects in the baby. However, most women in these studies stopped taking varenicline in the first few weeks of pregnancy, before the baby’s arms, legs and internal organs have formed. Use of varenicline in these women was therefore too early to assess whether it might cause birth defects if used after week 4 of pregnancy and later on during the first trimester.

Can use of varenicline in pregnancy cause miscarriage?

One study mentioned above does not currently raise any concerns relating to a link between varenicline use in early pregnancy and miscarriage. However, because only a very small number of women taking varenicline in early pregnancy have been studied further research is required before we can say more confidently that use of varenicline in early pregnancy does not increase the chance of miscarriage.

Can use of varenicline in pregnancy cause stillbirth?

Although there is currently no indication that use of varenicline in pregnancy causes stillbirth, a possible link has been analysed in only a very small number of women. Further research is therefore required to confirm that use of varenicline in pregnancy does not increase the chance of stillbirth.

Can use of varenicline in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

No studies have assessed the chance of preterm birth or low infant birth weight following use of varenicline in pregnancy. Research into this subject is therefore required.

Can taking varenicline in pregnancy cause learning or 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 investigated learning and development in children exposed to varenicline in the womb. Research into this subject is therefore required.

Will my baby need extra monitoring during pregnancy?

As part of their routine antenatal care most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth.

Because the effects of varenicline exposure on a developing baby are largely unknown your doctor may suggest additional monitoring if you have used varenicline in pregnancy to ensure that the baby is growing as expected.

Are there any risks to my baby if the father has used varenicline?

We would not expect any increased risk to your baby if the father used varenicline before or around the time you became pregnant.

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  

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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.

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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