Pre-eclampsia: How BHF research is helping mothers after pregnancy

Woman checking her blood pressure

Many women develop conditions such as high blood pressure or pre-eclampsia during pregnancy, with long-lasting consequences. Sarah Brealey finds out how BHF researchers are trying to change that.

Dealing with the real problems he sees in his patients is one of the things that drives Professor Paul Leeson’s research.

Half the time, Professor Leeson is a Consultant Cardiologist at the John Radcliffe Hospital in Oxford, supporting people with high blood pressure and heart problems. The other half of the time, he and his team at the University of Oxford try to find the solutions to these problems – focusing in particular on younger people at risk of heart and circulatory diseases.

One of the most significant of these groups is women who develop high blood pressure or pre-eclampsia in pregnancy. Although the condition usually goes away after childbirth, their risk of conditions such as coronary heart disease, stroke and vascular dementia remains higher for the rest of their lives. Research shows there is a 116% increase in risk of coronary heart disease for women who have had pre-eclampsia. Professor Leeson wants to change that.

He and his team are trying to find out whether better controlling blood pressure in the few weeks after birth can have long-term positive effects.

“At the moment, these women are really well managed in pregnancy and in hospital, and then once their blood pressure comes down, they are sent home, and only followed up with a blood pressure check every few weeks, or not at all,” says Professor Leeson.

“Then, a few years later, they will come back with hypertension (high blood pressure) and further changes to their heart and their brain, which are more difficult to manage. But if we manage these mothers really well in the early stages after birth, could we reduce future risk?”

How an app is helping mothers manage their blood pressure

Professor Leeson has already run a small study in collaboration with Professor Richard McManus, also at the University of Oxford, who is an expert in developing ways patients can manage their own blood pressure.

Around 45 women who had suffered from pre-eclampsia were provided with monitors when they went home from hospital and asked to measure their own blood pressure.

A smartphone app, designed by a team from the university’s Institute of Biomedical Engineering with input from the Department of Obstetrics, responded to the blood pressure readings by giving personalised instructions on how best to adjust their medications. Six months later, their blood pressure was lower than the group of women who received usual care.

Professor Leeson says: “The difference was on average about 5mm of mercury (mmHg) lower.” (Healthy blood pressure is below 120/80mmHg.) “That changes your trajectory significantly: it is enough to mean that you may develop hypertension several years later than you would have done, or that you don’t develop it at all.”

Six months later, their blood pressure was lower than the group of women who received usual care.

Now, thanks to £357,600 of BHF funding, the team has expanded to include a BHF Clinical Research Training Fellow, Dr Jamie Kitt, who will help run a bigger study, first testing the theory in a much larger group of women.

“This only needs to last for one to two months after pregnancy,” says Professor Leeson. “It is attractive as an idea because it is quite a short-term technique that could have long-term benefits.”

The second aspect of the research involves returning to the women involved in the first small study, to see if their blood pressure has remained lower three to four years later. The team will also look at changes in the bodies of women who have experienced pre-eclampsia.

They have previously looked at the heart and circulatory system five to 10 years after preeclampsia – some were found to have enlarged hearts (which puts them at risk of heart problems such as heart failure) and even changes in their brains.

“We looked at changes in blood vessels in the brain, years after the pregnancy, and there is damage linked to higher blood pressure, which means they are at increased risk of stroke and vascular dementia,” says Professor Leeson.

The BHF-funded research will continue this work in more detail, looking at changes to the blood vessels of the heart, brain and eyes. For the first time in this research, they are studying the blood vessels at the back of the eyes, because they are closely linked to the small blood vessels in the brain and may provide new information about how pre-eclampsia affects women’s bodies.

How soon will this research make a difference?

The project will run until 2022. “We are particularly excited that this is a definitive trial: it will show whether there is a blood pressure difference and whether that translates into a lower risk,” explains Professor Leeson.

“If it does, we will be able to make changes to how women are looked after quite quickly. This is a trial that can make a difference within a relatively short time – within a few years.”

This is a trial that can make a difference within a relatively short time - within a few years

Professor Leeson

Combining his research with his hospital role helps keep Professor Leeson motivated. “You are doing research that directly translates into benefits you can bring to patients. It is the back and forth between the patients and the research that makes it exciting.”

How the research could help children as well as their mothers

Further into the future, this research might offer ways to help the children of these mothers, who are also at higher risk of problems such as high blood pressure and stroke in later life. As Professor Leeson puts it: “Is there also something we can do in the early weeks of life to help get their health back on track?

“It is blue-sky thinking at the moment, but some of what we learn about how best to manage blood pressure in women after pregnancy could improve how we look after their babies. It might even be a way to prevent heart disease for the next generation.”

About pre-eclampsia

Pre-eclampsia affects up to one in 25 pregnancies in the UK, and gestational hypertension (high blood pressure in pregnancy) up to one in 10 pregnancies.

Pre-eclampsia usually develops after 20 weeks of pregnancy and is diagnosed by testing for protein in the urine and high blood pressure. The exact cause isn’t known, but it is thought to be a problem with the placenta, which supplies nutrients to the baby in the womb.

The NHS in England has announced that a new blood test for pre-eclampsia, which measures placental growth factor, will soon be available. It should allow for earlier and more accurate diagnosis.

The only cure for pre-eclampsia is to deliver the baby (specifically, the placenta), but both mother and child are still left with an increased risk of health problems later in life.

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