We are seeking the views of people who have received blood thinners during pregnancy or shortly after birth

If you think you can help us by taking part in a 1.5 hour paid workshop please contact Dr Fiona Sampson (email: f.c.sampson@sheffield.ac.uk, tel no: 0114 2220687) and read the information below.



During pregnancy and in the six weeks after delivery there is an increased risk of blood clots which develop in the legs or lungs. These can cause immediate and long term health problems  or even death. Small doses of blood thinners are used to reduce the risk of blood clots but also increase the risk of bleeding a little. People may be offered blood thinners if they have risk factors for blood clots. These risk factors include increasing age, being obese, previous serious illnesses and the type of delivery they had previously. 

We currently do not know exactly which people should be offered blood thinning medication to prevent blood clots during pregnancy and after delivery. Our research team are trying to understand how we can make the best decisions about who should be given blood thinning medication by reviewing the medical literature and then doing mathematical modelling. The research team will identify areas where we need more information, and what research should be carried out in future studies to provide this information.

We would like to understand how people feel about taking part in different types of future research that may help us to plug the gaps in our knowledge and contribute to reducing clots during pregnancy.

How can I get involved?

We are putting together a team of people to take part in a workshop to help advise the research team about what types of research studies they would be happy take part in, and what research outcomes are important to them. We would like to invite you to take part in this workshop if you:

  • Have been offered blood thinners during and/or after pregnancy


  • Have experienced a blood clot during or after pregnancy

We would like to speak to people from a range of backgrounds and with different risk factors for blood clots. 

What will I have to do?

We would like you to attend a workshop that will take place either face-to-face, or on an online platform such as Zoom. We will wait until nearer the time before we decide, and we will give you the choice where possible. You will be asked your thoughts about the different research options that we find and will discuss these in small groups. The discussion will take between 1-2 hours.


We offer a payment of £50 for your time and cover travel & out-of pocket expenses, if there are any. We will provide a claim form at the time of the workshop. This may affect means-tested benefits you are in receipt of – if you are concerned about this please check with us to clarify.

What do I do if I am interested in getting involved?

If you are interested in taking part in the study, please contact: Dr Fiona Sampson, Senior Research Fellow, University of Sheffield. Telephone 0114 2220687. Email f.c.sampson@sheffield.ac.uk

We have received ethical approval to undertake the research from the University of Sheffield. Further details about the whole study are on the next page or can be found here.


Summary of research


To use what we know already from existing research to work out what further research should be done to improve outcomes for women at risk of blood clots during pregnancy and in the early weeks after pregnancy.


Women who are pregnant or who have delivered a baby in the previous 6 weeks are at increased risk of blood clots that can cause serious illness or death. Small doses of blood thinning drugs can reduce the risk of blood clots but they also slightly increase the risk of bleeding. Currently whether or not a woman is offered blood thinning drugs to prevent blood clots depends on whether they are considered to have a high, medium or low risk of blood clots. This is worked out by their doctor based on factors such as their age, their previous illnesses, and for women who have given birth, the type of delivery they had. The tool used most often by UK doctors to decide if a patient is at high risk is one published by the Royal College of Obstetricians and Gynaecologists, but there are other alternative tools that could be used and each tool would select a different group of women to receive blood thinning drugs. 

We do not currently know whether we would be better to use an alternative risk assessment tool that results in either fewer or more women receiving blood thinning drugs. In addition, although there have been many clinical trials which show that blood thinning drugs reduce the risk of blood clots in other high risk groups, such as patients having operations, there have been fewer clinical trials of these drugs in women who are pregnant or who have recently delivered. Therefore, further research would be useful to help doctors decide which women should receive blood thinning drugs. 

Design and methods

The project will involve reviewing and bringing together all the existing research about this topic into a mathematical model. This model will allow us to explore whether it would be better to offer blood thinning drugs to more women to prevent more blood clots or whether it would be better to offer it to fewer women to minimise the numbers being exposed to an increased risk of bleeding. We will also use the model to work out where we currently lack the information we need to make the best decisions about using blood thinning drugs and what further research would be most valuable and cost efficient. We will then hold a workshop with women, to help us decide whether the future research studies suggested by the modelling would be acceptable to women and would capture the outcomes that matter to them. We would invite women to the workshop who have had the experience of being offered blood thinning drugs or who have experienced a blood clot during pregnancy or in the early weeks after pregnancy. We will also conduct a survey of doctors to ask if the proposed research will be practical to conduct. 

Patient and public involvement

We have a patient member as part of the project team who will help us develop and undertake this project. She will also act as a link to a broader community of patients through Thrombosis UK who we have worked with on two previous projects. 


This project is designed to help research funders decide what research to fund to improve outcomes for women at risk of pregnancy-related blood clots. A report on our research will be shared with research funders and accessible summaries of our findings will be shared with patient organisations and doctors who care for pregnant women.

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