The EPOS study: following women throughout pregnancy to understand miscarriage

Tommy’s are supporting research on over 1,080 women to help us understand why miscarriage happens. Within EPOS, two more studies are looking at how to tell early on if there are problems with a baby’s heart that could put it at risk, and the best ways to manage women with ectopic pregnancies.

Tommy’s are supporting research following more than 1,080 women from 5 weeks of pregnancy through to delivery. Called EPOS (the Early Pregnancy Observational Study), this will help us to understand why women miscarry, and see if we can find ways of telling when a woman is at risk.

Doctors will take samples of blood, urine, and swabs from the vagina to look for substances or bacteria that could help us understand why miscarriage happens. They will also carry out an ultrasound scan of the baby, and collect information about the women’s clinical history and demographics. Women will have follow-up visits every week in the first trimester, and one check-up in the second and third trimesters.

Early results show that there are significant chemical differences in the urine of women who miscarry, compared to women who have a normal pregnancy. We are now focusing on finding the specific chemicals involved.

This project and those below will help us to understand why miscarriage happens, to find problems earlier in pregnancy, and to work towards treatments to prevent miscarriage. 

All of these studies are still recruiting - find out about taking part in Tommy's clinical trials

The ABPEP study (Assessment of Biomarkers in Pregnancy of Unknown Location and Ectopic Pregnancy)

We are also studying women who have ectopic pregnancies, or pregnancies of unknown location (PUL). This is when a woman has a positive pregnancy test, but we can’t find where the egg is. Ectopic pregnancies are dangerous, and can be life-threatening. That is why we want to find the best way of managing women in this situation, and of telling when a PUL may be an ectopic pregnancy.

So far, we have recruited 750 women and collected over 12,000 blood and urine samples. We will analyse these, along with using statistical models, to find ways of telling whether or not a woman needs surgical intervention. We are comparing the levels of hCG – the “pregnancy hormone” – in urine and blood samples from women who have PUL, or an ectopic pregnancy. 

The PRECISE study (PRospective Early pregnancy Cardiac Imaging and anatomy ScrEening project)

As part of the EPOS study, we are looking at how we can better visualise the structure of babies’ hearts in the womb. A congenital heart defect, or CHD, is any problem with the structure of the heart that is present from birth. These are responsible for around 20% of miscarriages and stillbirths, and 30% of newborn deaths.

At the moment, CHD is only found when the baby is already 20 weeks old. We want to use technological advances to find CHD and other anatomical problems earlier. This will shed light on the causes of miscarriage, and give parents more information to help them make difficult decisions.


Tom Bourne, Phillip Bennett, David MacIntyre, Maya Al-Memar, Christoph Lees, Harsha Shah and external collaborators

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