(Date of issue: July 2015. 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?
Rituximab (MabThera®) is a type of medicine called a monoclonal antibody and may also be referred to as a biologic. It works by causing the destruction of a certain type of blood cell called a B-lymphocyte that is involved in the immune response. Rituximab is used to treat a number of different auto-immune conditions including rheumatoid arthritis, granulomatosis with polyangiitis, and microscopic polyangiitis (illnesses caused by inflammation of blood vessels). It is also used to treat certain types of lymphoma and leukaemia.
Is it safe to take rituximab in pregnancy?
There is no yes or no answer to this question. When deciding whether to take rituximab during pregnancy it is important to weigh up how necessary rituximab is to your health against any possible risks to you or your baby, some of which may depend on how many weeks pregnant you are. Use of rituximab in pregnancy may sometimes be considered necessary to keep leukaemia, lymphoma, or a serious autoimmune illness under control for the benefit of both the mother and her unborn baby. Your doctor is the best person to help you decide what is right for you and your baby.
This leaflet summarises the scientific studies relating to the effects of rituximab on a baby in the womb.
What if I have already taken rituximab 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 to make sure that you are taking the lowest dose that works.
Can taking rituximab 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.
No studies have specifically assessed whether pregnant women taking rituximab are at increased risk of having a baby with a birth defect. It is known that rituximab cannot cross the placenta in early pregnancy, and is therefore unlikely to have any direct effects on a developing baby. However, some medicines can indirectly affect the way that an unborn baby grows and develops, for example by affecting the mother’s circulatory system or the function of the placenta. Studies of the pregnancy safety of rituximab are therefore required.
A single study investigated babies born to a group of women who took biologics in early pregnancy. Some of the women in this study may have been taking rituximab but they were not studied separately. The findings may therefore not be directly relevant to women taking rituximab but are included for interest. This study showed that women taking biologics were not at increased risk of having a baby with a birth defect. Although the study suggested that use of biologics in pregnancy may be linked to having a baby with multiple birth defects, there were problems with the way in which the information was collected and analysed and it is unlikely that there is any true link but this needs to be confirmed by further research.
Can taking rituximab in pregnancy cause miscarriage?
Studying miscarriage rates in women taking rituximab and other monoclonal antibodies is complex as some of the mother’s illnesses that these medicines are used to treat are known to increase the chance of miscarriage.
To date, no studies have specifically assessed miscarriage rates in pregnant women taking rituximab, and scientific research into this subject is therefore required.
Can taking rituximab in pregnancy cause stillbirth?
No studies have specifically analysed stillbirth rates in pregnant women taking rituximab.
Can taking rituximab in pregnancy cause preterm birth, or my baby to be small at birth (low birth weight)?
No studies have specifically analysed rates of preterm birth of low birth weight babies in pregnant women taking rituximab.
Some of the underlying illnesses that rituximab is used to treat, may themselves increase the chance of preterm birth (before 37 weeks) and/or of a baby having a low birth weight (less than 2,500g). It will therefore be difficult to say whether rituximab has an effect on these outcomes, and future studies will need to address the effects of illness in the mother to answer this question.
Can taking rituximab in pregnancy cause other health problems in the child?
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.
No studies have been carried out to specifically investigate whether exposure to rituximab while in the womb increases the chance of learning and behavioural problems in the child, and research into this subject is therefore required
Infections after birth and risk to newborn babies with live vaccines Rituximab works by destroying a type of blood cell called a B-lymphocyte. These cells are part of the immune system and can be important to fight off infections. There are therefore theoretical concerns that babies who are exposed to rituximab in the womb may be more likely to develop infections after birth, although no studies have addressed this so far. There is a handful of case reports of babies who were exposed to rituximab in the womb having reduced numbers of B lymphocytes at birth, however, numbers of B lymphocytes returned to normal quickly, and the babies did not seem to be at increased risk of infection.
There are also concerns that babies who are exposed to rituximab in the womb could become ill if they receive a live vaccine. Live vaccines (e.g. rubella, measles, mumps, rotavirus) contain modified versions of the live viruses or bacteria that they protect against. They do not cause illness in people with healthy immune systems but are often not advised in people with low immunity. As a precaution, a doctor may recommend that immunisation of the baby with live vaccines is delayed for a few weeks or months after the mother’s final pregnancy dose of rituximab.
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.
Because the effects of taking rituximab in pregnancy are largely unknown, your doctor may suggest extra monitoring of your baby including more detailed scans for birth defects and monitoring of your baby’s growth in the womb. Women with some of the illnesses that rituximab is used to treat may also 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 rituximab?
There are case reports of seven live-born babies without malformations who were fathered by men who had taken rituximab around the time of conception. Most experts agree that the majority of medicines used by the father are unlikely harm the baby through affects on the sperm. However, more research on the effects of rituximab specifically and medicine use in men around the time of conception generally 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.
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.