An Investigation of Ethnicity Related Differences in Hypertensive Disorders of Pregnancy amongst Women living in the UK

Background

Approximately one in ten women will develop high blood pressure during pregnancy. Blood pressure problems in pregnancy can be serious, with risks to the mother and baby including stroke, preterm birth and stillbirth. In high-income countries including the UK, the likelihood of a woman developing high blood pressure in pregnancy and experiencing a related poor outcome, such as stillbirth, is influenced by her ethnicity.

Both Black and Asian women are more likely to be affected and experience poor outcomes than White women, with Black women in particular at highest risk. At the moment we do not understand why this is. It is possible that genes, health, economic and lifestyle differences are responsible, or that current treatments do not take into account the possibility that women from different ethnic groups respond differently to blood pressure drugs.

Aims In this study we plan to:

1. Find out why there are more blood pressure problems and related poor outcomes in pregnancy in some ethnic groups compared to others. 2. Carry out a study to investigate how women with high blood pressure in pregnancy respond to blood pressure drugs. Study design

PART 1. We will be looking at women's genes, general health, economic and lifestyle factors and blood pressure control in relation to blood pressure problems in pregnancy. We will use a health record dataset of over 60,000 pregnant women and their babies from a diverse South London population.

We will find out how many women develop high blood pressure in pregnancy and how this affects the health of the mothers and their babies. We will look at which ethnic groups are most affected. We will look at whether genetic ancestry (the percentage of a person's genetic material which they inherited from their ancestors), health, economic and lifestyle factors or blood pressure control are most related to poor outcomes in blood pressure problems in pregnancy.

PART 2. We will investigate the best way to carry out a study to evaluate response to blood pressure drugs in different ethnic groups in pregnancy. In a pilot study, we will recruit 96 pregnant women of different ancestries with high blood pressure taking treatment (labetalol or nifedipine, both commonly used drugs to lower blood pressure in pregnancy).

We will ask them to wear a 24-hour blood pressure measurement device (which we know pregnant women find acceptable), and to have an extra blood test to look at genes and biological markers we think are related to blood pressure drug response. Results from this study will allow us to plan a larger trial in the future.

Impact

Ultimately our aim is to improve the care of women with blood pressure problems in pregnancy. If we can identify women at highest risk early in pregnancy we can monitor and treat these women more intensively. Understanding who is most likely to respond to blood pressure drugs also has the potential to personalise treatment of blood pressure in pregnancy.

Results communication

We know that the results of this study will be very important for women and their babies. We will work with women who have experienced blood pressure problems in pregnancy through local Patient and Public Involvement groups and Action on Pre-eclampsia (APEC) charity patient experts to ensure that the results of this work are shared in a sensitive and easy-to-understand way.

We will also publish our results in scientific journals. Important findings from our study can then benefit women all over the UK.