Around 5% of pregnant women have pre-existing high blood pressure. This is called chronic hypertension – a chronic illness is one that lasts for long periods of time, or that keeps on coming back. Chronic hypertension can lead to serious problems for both mother and baby during pregnancy, and is one of the main causes of maternal death in the UK. Mothers are at risk of stroke and harm to their kidneys, while their babies may be born early or underweight, with a higher chance of stillbirth. At the moment, it is unclear which drugs are best at controlling blood pressure during pregnancy.
Tommy’s supported researchers have enrolled around 110 pregnant women in a study to compare two drugs that control blood pressure: NifeDipine and Labetalol. This is an early stage of what we hope will be a national trial across many different centres. We want to find the best way of treating chronic hypertension during pregnancy without causing harm to mother or baby. We will also look at whether the ethnicity of pregnant women changes which drug works best.
Scientists looked at the response to the two drugs by seeing how well the placenta, kidneys and blood vessels were working, through measuring substances in the women’s blood and urine. They also tested the stiffness of the women’s blood vessels, using a non-invasive inflatable cuff that is placed around the arm. They found that the drugs had different effects on the blood pressure in the aorta, the large artery that takes blood away from the heart to give the body oxygen. This difference may be important in telling which drug will best help mother and baby to stay healthy during pregnancy.
Scientists have also discovered that women with chronic hypertension, particularly women from ethnic minorities, were more susceptible to disease (with high rates of adverse outcomes, such as stillbirth and preterm labour) during pregnancy.
The results of this study have allowed us to apply for funding to run a larger, national trial. In the future, results from this research could improve the care of many women suffering from chronic hypertension, and save babies from stillbirth and premature birth.
This study takes place in a Tommy's centre and is funded by Tommy's and Guy’s and St Thomas’ CharityHide details