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Pregnant women who have chronic hypertension (long-term raised blood pressure), putting them at greater risk of developing a potentially dangerous condition called ‘pre-eclampsia’.


Self-monitoring of blood pressure at home to gain better control of blood pressure.


  • To see if a larger trial of self-monitoring would be possible
    • To see if pregnant women with chronic hypertension find monitoring their own blood pressure acceptable.
    • To identify the most appropriate ‘outcome measures’ for blood pressure control to use in a larger trial. For example, if people who self-monitor  have fewer visits to the doctor or lower blood pressure compared to people in usual care.
    • To see how NHS resource  use (e.g. hospital admission rates, number of GP visits and so on) differs between women who self-monitor and those in usual care.

Why this is important

Pre-eclampsia is a condition which affects pregnant women, and can put both mother and baby at risk. The warning signs of pre-eclampsia include high blood pressure and protein in urine.

Around 10-15% of women develop high blood pressure during pregnancy.

If not treated pre-eclampsia can lead to seizures, kidney and blood clotting problems. For babies, it can lead to low birth weight and an increased risk of dying before birth. Treatment is usually in the form of blood pressure lowering drugs.

5% of women have existing chronic hypertension before starting pregnancy. This puts them at a higher risk of developing pre-eclampsia than those without chronic high blood pressure.

Because of this, their blood pressure is closely monitored and managed via more frequent antenatal clinics.

However, despite more frequent monitoring, women's blood pressure can rise between these visits. This puts mother and baby at risk.

One possible solution to this problem is pregnant women self-monitoring their blood pressure at home.

Self-monitoring at home may be able to detect rising blood pressure sooner, and women can then share this information with their care teams. This could lead to earlier diagnosis and treatment to prevent complications developing.

Care teams would be able to use the more frequent blood pressure readings to make better and timelier treatment decisions. For example, by raising or lowering blood pressure medication as needed.

This could lead to improved health outcomes for mothers and their babies, and may prove to be a cost-effective way to improve their care.


Our 'target population' will be women with chronic high blood pressure, but no diagnosis of pre-eclampsia.

We will approach such women attending for antenatal care at the John Radcliffe Hospital, Oxford, St Thomas’ Hospital, London, and New Cross Hospital, Wolverhampton.

Those women who agree to take part will be randomly assigned to one of two groups: usual care or usual care plus blood pressure self-monitoring.

For every woman in the usual care group we will place two in the self-monitoring group. We aim to recruit 20-30 women at each site over a twelve month period.

Those in the self-monitoring group will be taught how to use a home blood pressure monitor. They will be asked to use this once a day and record the results in a diary.

They will also be given advice about any action they should take if their blood pressure is too high or too low.

Both groups will be asked to record their medications and the amount they take in diaries.

We will meet with these women as part of routine clinical visits at 20, 28, and 34 weeks pregnancy, and 6 weeks postnatal.

At each meeting, we will collect self-monitoring and medication diaries, and blood pressure monitor data.

As this is a feasibility study – carried out to determine if a much larger trial would be possible – the main focus (the ‘primary outcome measures’) will be on monitoring:

  • how many women agree to take part;
  • how many women stay in the trial; and
  • how well they stick to the daily blood pressure monitoring.

A range of ‘secondary outcome measures’, used to gauge the effectiveness of self-monitoring and other effects, will also be collected. These will include:

  • comparing different measures of how well blood pressure is controlled between the two groups;
  • looking at differences in how blood pressure lowering drugs are prescribed between groups;
  • comparing resource use (such as number of GP visits, or use of NHS services and time) between the two groups; and
  • interviews with women and clinicians to understand their experiences of blood pressure self-monitoring and how acceptable they find it and gather any suggestions for improving the approach.

How this could benefit patients

This project has the potential to improve the health of women with chronic high blood pressure in pregnancy. This could lead to fewer complications during pregnancy, protecting the health of both mother and baby.

Additionally, if self-monitoring of blood pressure reduces the use of NHS resources, this will free them up for other uses across a wide range of other conditions.

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