Casirivimab and Imdevimab

Date: December 2021, Version 1.0

What is it?

Ronapreve® is the brand name for a medicine that contains a mix of two synthetic (manmade) antibodies (casirivimab and imdevimab). These antibodies bind to the spike protein that sits on the surface of the COVID-19 virus. It works by blocking the way the virus enters cells, and it can also help your body to clear infection.


What are the benefits of Ronapreve in pregnancy?

Ronapreve is used in unvaccinated people who are at high risk of developing severe COVID-19 illness. It lowers the risk of being admitted to hospital, and of dying due to COVID-19.

Pregnant women are at increased risk of severe COVID-19 illness. Severe COVID-19 has been linked with a higher risk of babies being born too early, which can result in serious problems for the baby after delivery and in later life. There is also a higher risk of stillbirth. Synthetic antibodies like those in Ronapreve help your immune system to fight the virus, lowering the risk of severe illness.


Are there any risks of using Ronapreve in pregnancy?

Synthetic antibodies have been used in pregnancy for many years. They are routinely used to prevent conditions like rhesus disease (anti-D injections).

Ronapreve is a newly developed medication and has not yet been tested in pregnancy. However, because Ronapreve only binds to the spike protein of the COVID-19 virus, and does not bind to proteins that are made by the developing baby or placenta, it is not thought to be harmful to the baby.


Are there any alternatives to Ronapreve in pregnancy?

Yes. Other drugs can help prevent severe COVID-19 infection in those who have tested positive. One of these (sotrovimab, brand name; Xevudy®) is a synthetic antibody which also bind very specifically to the COVID-19 virus. As with Ronapreve, it is thought unlikely to be harmful in pregnancy.

Molnupiravir, is an antiviral medicine that can stop early COVID-19 infection from developing into serious illness. It is taken in tablet form by people with a positive COVID-19 PCR test and mild to moderate symptoms who are at risk of severe COVID-19. Unfortunately, there are concerns that it could be harmful to the developing baby, and it is not recommended in pregnancy. For more information, please see here.

Vaccination against COVID-19 is strongly encouraged for all pregnant women in the UK. It can reduce the chance of infection and help to prevent serious illness, and may reduce the need for other medicines. For more information, please see here.

No treatment

What if I prefer not to have any treatment in pregnancy?

Pregnant women are at increased risk of severe COVID-19 illness, which has also been linked with a higher risk of premature delivery and stillbirth. Your doctor will only offer medicines to treat COVID-19 when absolutely necessary and will be happy to talk to you about any concerns that you might have.

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 healthcare provider. They can access more detailed medical and scientific information from

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.