(Date: February 2019. 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 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?

Lenalidomide is used to treat certain blood cancers (multiple myeloma, mantle cell lymphoma, and myelodysplastic syndrome). Lenalidomide is a very similar medicine to thalidomide, which is known to cause birth defects in babies exposed in the womb.

Is it safe to take lenalidomide in pregnancy?

No. Lenalidomide has been shown to cause birth defects in animal studies and is structurally similar to thalidomide which caused miscarriage and severe birth defects in thousands of babies who were exposed in the womb in the 1960s. Although there are no human studies of lenalidomide use in pregnancy, it has to be assumed that lenalidomide may affect a baby in the same way as thalidomide

Women and girls who need to take lenalidomide and who may become pregnant are therefore required to be in a pregnancy prevention programme (PPP). This includes:

• Agreeing to use reliable contraception, or to abstain from sexual intercourse during treatment and for one month afterwards.

• Having a negative pregnancy test one month before starting treatment, and then having repeat pregnancy tests every month during treatment and one month after treatment has stopped.

• Signing a consent form to say that your doctor has explained the risks to a pregnancy of lenalidomide treatment and that you understand these risks.

Because lenalidomide stays in the body for some time after you stop taking it, it is important to avoid getting pregnant for at least one month after the last dose.

What if I have already taken lenalidomide during pregnancy?

If you are pregnant or think you may be pregnant and are taking lenalidomide you should urgently contact your doctor or midwife.

What type of birth defects are caused by taking lenalidomide in pregnancy?

It is assumed that lenalidomide will cause similar birth defects to those caused by thalidomide, which include:

• Reduced/missing arms (and/or legs, but this is rarer)
• Missing thumbs, or thumbs with an extra bone (triphalangism)
• Club feet
• Extra toes
• Reduced or missing ears and deafness
• Paralysis of facial nerves
• Abnormally small eyes and other eye malformations
• Heart defects
• Defects of the internal organs, including kidneys, brain, digestive and reproductive systems (it is not certain whether all of these birth defects were caused by thalidomide)

Some children exposed to thalidomide have one of these birth defects while some have several. The type and number of birth defects relates to the exact stage of pregnancy when thalidomide was taken and how many times it was used, although birth defects have been reported following a single dose. It is assumed that exposure to lenalidomide will have similar effects.

Can taking lenalidomide in pregnancy cause miscarriage or stillbirth?

No human studies have been carried out to assess whether lenalidomide use in pregnancy causes miscarriage or stillbirth. However, it is assumed that lenalidomide will have similar effects on a pregnancy to thalidomide, which has been linked to both miscarriage and stillbirth.

Can taking thalidomide 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.

A small study has shown that taking thalidomide in early pregnancy may be linked to an increased risk of learning problems and autism spectrum disorder (ASD) in children, and so we have to assume that lenalidomide might pose the same risk. 

It is unknown whether thalidomide (or therefore lenalidomide) taken after the first trimester of pregnancy might also affect a baby’s developing brain, leading to problems with learning and behaviour.

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.

Women who have taken lenalidomide in the month before pregnancy or during the first trimester and who decide to continue with their pregnancy will be offered more detailed anomaly scans.

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

When a man takes lenalidomide, small amounts enter his semen. Men taking lenalidomide are therefore advised to use condoms during sexual contact with pregnant women or women of childbearing potential because lenalidomide present in semen may pose a risk to a developing baby.

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.



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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