Understanding how heart disease risk begins before you’re born

Most people know that your lifestyle and your genes can affect your chances of developing common conditions, including heart and circulatory diseases.

Did you know that what happens when you are still in your mother’s womb can also influence your risk of diseases in later life? In fact, your parents’ health and lifestyle before they even thought of having a baby will have played a role in your health too.

The BHF has funded and is still funding several large studies to find out more about this.

The Barker hypothesis

In the 1990s we helped to fund ground-breaking work by Professor David Barker at the University of Southampton, which revealed that premature babies, as well as those who have a low weight at birth, go on to develop some diseases more frequently in later life, including high blood pressure, coronary heart disease and type 2 diabetes.

Professor Barker’s theory, called “Barker hypothesis” or sometimes the “foetal origins of disease hypothesis”, proposes that the development of heart and circulatory diseases, type 2 diabetes and even obesity in adulthood might be triggered by circumstances of our development in our mother’s womb. This theory was controversial at the time but has now been confirmed by other studies across the world.

Since then, many studies have tried to identify the factors that could affect this.

This field is now known as epigenetics – when your genes are affected in ways that don’t involve changes to the DNA sequence – in other words, other factors cause genes to be switched on or off. BHF Professor Mark Hanson has started a programme of research in this field at the University of Southampton. Though still work in progress, his team is beginning to show how a pregnant mother’s health affects the development of the placenta, which controls the supply of critical nutrients to the unborn baby. Changes in this supply can cause genes to be switched on or off– altering the lifetime risk of heart and circulatory and other diseases.

Knowing more about how a mother’s health affects her child’s health could help women planning a pregnancy or who are pregnant, to make the best decisions for themselves and their child’s health.

Maternal obesity during pregnancy affects the long-term health of children

Supported in part by the BHF, Professor Rebecca Reynolds at the University of Edinburgh extended Professor Barker’s hypothesis to understand whether a mother’s weight when she is pregnant cany affect the risk of her child dying from heart and circulatory diseases in later life. They studied data from more than 37,000 people born between 1950 to 2013. They discovered for the first time that the adult children of women who had obesity when pregnant were more likely to die early and were more likely to have a heart attack.

This information will help to inform new guidance from the National Institute of Health and Care Excellence (NICE) on weight management before, during and after pregnancy. This is an important issue, as half women of childbearing age have either excess weight or obesity.

Finding out how our lifestyle and environment can influence the heart health of our children

We have also been supporting the Southampton Women’s Survey (SWS), which launched in 1998 and is still running. Its aim is to learn more about the diet and lifestyle factors that influence the health of women and their children. It followed women from before they became pregnant (it is the only study of its kind in Europe to have done this), through pregnancy and is now studying the health of their children until they were 13 years old and even beyond.

An early finding of the study was that few women were following health recommendations in the three months before pregnancy. Currently, women who are planning a pregnancy are advised to take folic acid and to stop smoking, as well as other recommendations around diet, exercise and alcohol, but in most cases these were not being followed. Using findings from the survey, Professor Hanson highlighted to the Government the importance of ‘preconceptual health’ and the missed opportunities to promote health in women of reproductive age. Evidence from the study has also helped to provide guidance for healthcare professionals working with women around the time of pregnancy.

The Southampton Women's Survey has also taught us more about how a mother’s diet affects the health of her children. In 2015, Professor Keith Godfrey and colleagues showed that higher oily fish consumption in pregnancy is associated with healthier blood vessels in their children (this was measured by looking at the stiffness of the aorta, the main artery in your body). These findings show that eating oily fish in pregnancy may have potential long-term benefits for the child’s health. Whilst the finding has not yet directly transferred into guidance for expectant mothers, it has added what we know about the importance of eating oily fish.

First published 1st June 2021