Mycophenolate Mofetil (MMF)

(Date: January 2016. Version: 2.1)

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?

Mycophenolate mofetil (CellCept®) and another form of the same medicine called mycophenolic acid (Myfortic®) are used, often in combination with other medicines, to prevent organ rejection in people who have received kidney, liver or heart transplants and occasionally to treat auto-immune illnesses including psoriasis and lupus.

Is it safe to take MMF in pregnancy?

Taking MMF during the first trimester of pregnancy can cause miscarriage and birth defects in the baby (see below). Use of MMF in women or girls who could become pregnant (even if they are not planning a pregnancy or are not sexually active at the time) is therefore not generally advised but may occasionally be considered necessary if other treatments to prevent the rejection of a transplanted organ, or for serious autoimmune illness have not worked.

In October 2015, the European Medicines Agency published guidance on preventing pregnancy in women and fertile girls for whom MMF is the only suitable treatment. To avoid pregnancy whilst on MMF, patients should have two negative pregnancy tests before starting MMF (one 8 to 10 days before, and the second immediately before starting MMF) and should use two forms of contraception that are considered to be effective, whilst taking MMF and for 6 weeks after stopping MMF treatment. Your doctor will be able to give you more information on the types of contraception that can be used at the same time and would be appropriate for you to consider in this situation.

What should I do if I am taking MMF but would like to start a family?

Any woman who is taking MMF and is planning a pregnancy should speak to her doctor to discuss the possibility of switching to a different medicine before she conceives. However, some women may need to take MMF during the first trimester of pregnancy. Your doctor will be able to help you to weigh up how necessary MMF is to your health against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are.

This leaflet summarises the scientific studies relating to the effects of MMF on a baby in the womb. It is advisable to consider this information if you are taking MMF and are pregnant or could become pregnant in the future, even if you are not currently planning on having children. Your doctor is the best person to help you decide what is right for you and your baby.

What if I have already taken MMF during pregnancy?

If you are pregnant or think you may be pregnant and are taking MMF, you should speak to your doctor as a matter of urgency. He/she will then be able to advise you about what you need to do next. It is very important that you do not suddenly stop taking MMF as this could be dangerous to you, and also to your baby if you are already pregnant. Do not make any change to your medication without first talking to your doctor.

What is the chance that taking MMF in pregnancy will cause a miscarriage?

The three small studies that have investigated this showed that between 4 and 5 out of every 10 women who took MMF in early pregnancy had a miscarriage. However, the underlying illnesses that MMF is used to treat, as well as other medicines that the women in these studies were taking, may themselves increase the chance of miscarriage. Much more research into this subject is therefore required.

What is the chance of MMF use in pregnancy causing birth defects in the baby?

The two studies that have investigated this suggest that overall, 21 to 26 out of every 100 babies exposed in the womb to MMF during the first trimester have a birth defect. This is much higher than in the general population where major birth defects occur in two to three out of every 100 babies.

The types of birth defects that have been shown to be caused by MMF include:
• Microtia (abnormally small ears), the ear canal being narrower than normal or completely closed resulting in deafness.
• Cleft lip and/or palate, micrognathia (abnormally small lower jaw).
• Micropthalmia (abnormally small eyes), a gap called a coloboma in parts of the eye including the iris (the coloured part of the eye) or retina (the light-sensitive layer at the back of the eye) that can lead to eyesight problems, eyes that are further apart than normal.
• Serious heart defects.
• Diaphragmatic hernia (a hole in the baby’s diaphragm, which is the muscular sheet that separates the lungs and the abdomen or tummy. As a result, the baby’s liver and bowel are pushed up into the chest squashing the baby’s lungs which do then not develop properly).
• Oesophageal atresia (where the tube between the mouth to the stomach has not formed properly and so the two are not connected).

Some MMF-exposed babies may have just one of these malformations, while some have more than one and others have none.

Each woman’s personal risk of having a baby with birth defects caused by MMF will depend on a number of things. The most important may be the stage of pregnancy at which she took MMF (one small study found that all of the babies with birth defects caused by MMF had been exposed during the first 8 weeks of pregnancy). Other factors that determine risk may include the other medicines that a woman is taking, her underlying illness, and her and her baby’s genetic make-up, but no scientific research has been carried out to confirm this.  There is also currently no scientific proof that taking a lower dose of MMF reduces a woman’s chance of having a baby with birth defects and there is no known ‘safe dose’ of MMF.

Can taking MMF in pregnancy cause stillbirth?

There are currently no studies that have investigated whether women who take MMF in pregnancy are at increased risk of stillbirth.

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

There are currently no scientific studies that have investigated whether use of MMF in pregnancy increases a woman’s chance of having a preterm birth or a baby with a low birth weight.

Women who have received an organ transplant or who have serious auto-immune disease may have a higher chance of preterm birth (before 37 weeks) and/or of their baby having a low birth weight (less than 2,500g) due to their underlying illness. It is therefore very important that future studies on birth weight and preterm delivery separate out the effects of the mother’s illness so that any effect of MMF can be accurately assessed.

Can taking MMF in pregnancy cause other health problems in the child?

Infections after birth
MMF works by reducing the immune response. A healthy immune system is important to fight off infections, and there are therefore concerns that babies who are exposed to MMF in the womb may be more prone to infections after birth. However, no studies have investigated whether this is the case as yet, and this is an important question that needs to be addressed by future research.

Learning and behavioural problems
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.

There is no known link between taking MMF in pregnancy and learning or behavioural problems such as attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder in the child. There are, however, no scientific studies that have specifically investigated a link with these problems.

Will my baby need extra monitoring?

Women who have taken MMF during the first trimester and who decide to continue with their pregnancy should be offered more detailed anomaly scans from as early as around 12 weeks of pregnancy. It is however, harder to see birth defects at this stage of pregnancy, which is why the main scan for birth defects is generally offered at around 20 weeks of pregnancy. It is important to understand that scans are not able to pick up all birth defects and cannot predict whether a baby will have problems with learning.

In general, women who have received an organ transplant or who have serious auto-immune illness will be more closely monitored during pregnancy to ensure that they remain well throughout and that their baby is growing and developing as expected. 

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

Two reports, in which information from the United States National Transplant Pregnancy Registry was analysed, suggest that babies of men who took MMF around the time of conception   were no more likely to have a birth defect than babies in the general population. The first report reviewed information on 74 babies fathered by men who were treated with MMF. The second more recent report included around 200 live born babies. However, because other possible effects have not been ruled out men who are taking MMF are advised to use condoms during sex and to continue doing so for 90 days after stopping treatment. Their female sexual partners are also advised to use effective contraception during this time. 

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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