Interferon beta

(Date: February 2016. 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 Public Health England 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?

Interferon beta is a medicine that is prescribed to treat multiple sclerosis. It is given by injection and works by reducing inflammation in the body.

Is it safe to use interferon beta in pregnancy?

There is no yes or no answer to this question. When deciding whether to use interferon beta during pregnancy it is important to weigh up how necessary interferon beta is to your health against any possible risks to you or your baby, some of which might depend on how many weeks pregnant you are.

It is important to appropriately treat conditions such as multiple sclerosis in pregnancy. In some women the symptoms of multiple sclerosis improve as pregnancy progresses and a doctor might then advise that certain treatments can be reduced or stopped; for other women treatment with interferon beta in pregnancy might be considered the best option for both mother and baby.

You should not alter the dose of any of your medicines without medical supervision. Your doctor is the best person to help you decide what is right for you and your baby.

What if I have already used interferon beta during pregnancy?

If you have taken any medicines it is always a good idea to let your doctor know that you are pregnant so that you can decide together whether you still need the medicines that you are on and, if so, to make sure that you are taking the lowest dose that works.

Can using interferon beta 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.

Thirteen studies have been carried out that together include around 1,100 babies born to women who used interferon beta in pregnancy. Twelve of these studies provided no evidence that use of interferon beta in pregnancy increases the risk of birth defects in the baby. Although the thirteenth study showed a possible increase in risk, it included just 16 pregnant women, and only two of the babies exposed in the womb to interferon beta had birth defects. Due to this, the findings are not considered to be reliable.

Can using interferon beta in pregnancy cause miscarriage?

Studies that together include around 800 women using interferon beta in early pregnancy have provided no evidence that use increases the risk of miscarriage. Although this is reassuring, because these studies did not use the most up-to-date statistical techniques, further large studies are required to confirm this finding.

Can using interferon beta in pregnancy cause stillbirth?

No studies have investigated whether rates of stillbirth are increased in women who use interferon beta in pregnancy.

Can using interferon beta in pregnancy cause preterm birth?

Nine studies that together include around 600 babies born to women who used interferon beta in pregnancy have investigated a link with preterm birth. Eight of these studies provided no evidence that use of interferon beta in pregnancy increases the risk of preterm birth. Although the ninth study showed a possible increase in risk, it is thought that this might have been at least partly due to the fact that the women using interferon beta were likely to have more severe multiple sclerosis than women not taking interferon beta, and that the severity of their illness might have increased the risk of preterm birth.

Can using interferon beta in pregnancy cause my baby to be smaller than normal at birth or to have a low birth weight (less than 2,500g)?

Studies of around 600 babies exposed to interferon beta during pregnancy have provided mixed results about whether treatment with beta interferon in pregnancy might affect the growth of a baby in the womb. 

It is also not clear whether low birth weight (less than 2,500g) is more common in babies exposed to interferon beta in the womb as no large studies have addressed this. 

Further studies are required to determine whether the growth of the baby in the womb can be affected by a mother’s multiple sclerosis, and if so whether treatment with interferon beta during pregnancy might help a baby to grow normally, or possibly to impair a baby’s growth.

Can using interferon beta 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.

Learning and behaviour has been studied in around 50 babies and children who were exposed to interferon beta in the womb. Although there is currently no indication that exposure to interferon beta in pregnancy is linked to learning and behavioural problems in the child, much larger studies that assess many different aspects of learning and behaviour are required to confirm this.

Will my baby need extra monitoring during pregnancy or after delivery?

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. Using interferon beta in pregnancy is not expected to cause problems that would require extra monitoring of your baby during pregnancy. However, women with multiple sclerosis might be more closely monitored to ensure that their baby is growing and developing as expected.

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

No studies have specifically investigated whether interferon beta 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

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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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