Up until now, women’s reproductive health and women’s risk for cardiovascular outcomes have been thought to be independent. As such, there has been very little research on any potential correlation between women’s-health-related risk factors and cardiovascular disease or stroke. 

However, according to a new study from The BMJ, there is some positive correlation between female reproductive health and a higher risk of cardiovascular outcomes. 

The Study

To conduct the study, a team of UK researchers conducted what is known as an “umbrella review.” In an umbrella review, researchers use the highest level of evidence from other reviews that are relevant to the research question at hand.

In this case, the UK researchers searched relevant, pre-existing research databases for systematic reviews and meta-analyses that investigated links between women’s reproductive health and risk of cardiovascular disease. Thirty two  total reviews were included in this evaluation, with average follow-up periods of 7-10 years within the reviews they consulted. 

Results

Through their study, researchers at BMJ pointed to several women’s health factors that were associated with a higher risk of cardiovascular outcomes. However, for as many health factors that were associated with a higher risk, there were more that were not associated with cardiovascular outcomes at all. 

Here is a breakdown of their findings.

Women’s Health Factors with a Positive Correlation

In total, The BMJ found a total of ten women’s health factors that were correlated with a higher risk of cardiovascular problems:

• Starting periods early (aka early menarche)
• Use of combined oral contraceptives
• Polycystic ovary syndrome
• Miscarriage
• Stillbirth
• Preeclampsia
• Diabetes during pregnancy
• Preterm birth
• Low birth weight
• Early menopause

Besides pre-eclampsia, all of the factors on this list were correlated with up to a twofold risk of cardiovascular outcomes. Pre-eclampsia, however, was correlated even higher with a fourfold risk of heart failure.

Why were these factors correlated with a higher risk of cardiovascular outcomes? Possible explanations for these associations include a variety of other medical factors. A person’s family medical history, genetics, weight, and chemical imbalances from use of hormonal contraceptives all have to do with both their reproductive health and their cardiovascular health. Plus, a positive correlation between these health factors and higher risk of cardiovascular outcomes was also found in patients with high blood pressure and cholesterol levels.

Women’s Health Factors with No Correlation or Negative Correlation

While use of combined oral contraceptives correlated with a higher risk of cardiovascular outcomes, other birth controls and medicines did not. When it came to the use of progesterone-only contraceptives or non-oral hormonal contraceptive agents, neither was found to be associated with a higher risk of cardiovascular issues. Fertility treatment was likewise not found to have a negative cardiovascular association.

On the other hand, breastfeeding was actually found to be associated with a reduced risk of cardiovascular disease.

Study Limitations and Other Notes

While this is the first indication of a correlation between women’s reproductive health and higher risk of cardiovascular issues, the researchers were quick to note that this study is by no means conclusive. For one, in their umbrella review, there was a non-negligible amount of missing data. 

What’s more, the study is further flawed due to the fact that the reports relied largely on observational evidence. No new study was conducted- the results that researchers found were based solely on data from previous studies. As such, unmeasured factors (also known as confounding factors) could have had an effect on the outcomes that the researchers observed. 

Even so, we do now have reason to believe that a woman’s reproductive health may not be completely independent of her risk for cardiovascular disease. The researchers behind this study hope that more research will be done into this subject in the future, and that reproductive risk factors become more widely incorporated into risk assessments for cardiovascular disease.