An earlier first birth, a higher number of live births, and starting periods at a younger age are all linked to a higher risk of cardiovascular problems in women, according to new research published in the Journal of the American Heart Association. The study, led by Imperial College London researchers, provides evidence for a causal relationship between sex-specific factors and cardiovascular disease in women, and identifies potential ways to mediate this increased risk.
The study is the most comprehensive analysis to date of reproductive factors specific to women and their links to a range of cardiovascular diseases, including atrial fibrillation (irregular heart rate), coronary heart disease, heart failure, and stroke. The researchers hope it will help doctors to better understand and monitor women’s risk factors and intervene where appropriate.
Imperial College London researchers led a team that analysed genetic data linked to women’s age at first birth, their number of live births, age at menarche, and age at menopause. They looked at previous studies involving more than 100 000 women.
Observational research has previously identified that some reproductive factors are associated with cardiovascular disease for women in later life, but such studies are limited as they have been unable to support a causal relationship.
By using a statistical technique called Mendelian Randomization, the researchers were able to show a link between the genes that predict reproductive factors and the risk of multiple cardiovascular diseases. This type of analysis enables researchers to cut through the noise of factors such as diet, economic background and physical activity levels that can otherwise complicate the overall picture, and so it points to causal links.
The analysis showed that earlier first birth, a higher number of live births, and earlier menarche were associated with a higher risk of atrial fibrillation, coronary artery disease, heart failure, and stroke in women. However, it did not find an association between the age of menopause and cardiovascular disease.
The researchers also found that much of the increased risk for earlier menarche resulted from this factor being associated with women having a higher body mass index (BMI). This means that lowering a person’s BMI could help to reduce this risk. The increased risk for earlier first birth could be partly limited by acting on traditional cardiometabolic risk factors, such as BMI, high cholesterol and high blood pressure.
Dr Maddalena Ardissino, lead author of the study, from the National Heart and Lung Institute at Imperial College London, said: “Women are often mischaracterised as being at low risk for cardiovascular disease, leading to delays in diagnosis. Even when they are diagnosed, they tend to receive less targeted treatment than men.
“This study shows a clear link between reproductive factors and cardiovascular disease. This doesn’t mean that women should worry if they’ve had their period at a young age, or if they had an early first birth. Our research shows that the additional risk of cardiovascular disease can be minimised if traditional risk factors like BMI and blood pressure are well-controlled. These findings highlight the need for doctors to monitor these risk factors closely in women and intervene where needed.”
Dr Fu Siong Ng, senior author for the study, said: “Many of the previous studies on cardiovascular disease have focused on men, but our research shows that there are sex-specific factors that influence the risk for women.
“While we cannot say exactly how much these factors increase the risk of cardiovascular disease, our study shows that reproductive history is important and it points towards a causal impact. We need to understand more about these factors to make sure that women get the best possible care.”
Further research is needed to understand the extent of the relationship between reproductive factors and cardiovascular disease risk, such as whether there is a linear or non-linear relationship between a factor and increased risk.
Source: Imperial College London
