Women who have more than one or two children increase their risk of a major heart attack in future by as much as 40 per cent, UK researchers have found.
The study by academics at the University of Cambridge showed the biggest risks were to mothers with five or more children, but increased with each successive child.
Pregnancy and childbirth each put significant strain on the heart, the researchers suggest, and this is in addition to the stress and demands of raising a larger family which leaves less time for self-care.
Having five or more children was also associated with a 30 per cent increased risk of heart disease – the major cause of heart attacks – as well as a 25 per cent increased risk of stroke and a 17 per cent increase in the risk of heart failure compared with one or two children.
The authors said they hoped the findings would help provide “extra motivation” for parents of large families to take extra steps to protect their heart in other ways, such as diet and exercise.
Previous studies have suggested that breastfeeding may help protect the heart, but this research found it did not completely offset the extra risk of having more children.
The study, which is being presented at the British Cardiovascular Society Conference in Manchester, saw the team study data from more than 8,000 white and African-American women from the United States who were aged 45 to 64.
It also looked at women who had a history of pregnancy loss, through miscarriage or other factors, and found these women had a 60 per cent higher risk of heart disease than women who had one or two children.
They said this is likely to reflect underlying health problems that increase the risk of pregnancy loss as well as heart disease and heart failure.