Women diagnosed with infertility have a 14 percent higher long-term risk of non-fatal stroke, according to a large, global study.
Data from over 600,000 women from Australia, China, Japan, Netherlands, Sweden, UK and USA was analysed to determine if reproductive history had an impact on chronic diseases, including stroke. Previous research in the area has been inconclusive.
'It's possible infertility, miscarriage, and stillbirth could increase stroke risk because of other health issues. These could include endocrine disorders (low oestrogen or insulin resistance), inflammation, problems with endothelial cells that assist in blood flow, psychological disorders, unhealthy behaviours (such as smoking) or obesity,' the authors said.
In addition to the findings for women with infertility, researchers found women who had had a miscarriage had an 11 percent higher chance of non-fatal stroke and eight percent increased risk of a fatal stroke, and women who had experienced stillbirth were at a 31 percent increased risk of non-fatal stroke and seven percent increased risk of fatal stroke. These risks increased for repeat miscarriage and stillbirth. These findings were published in the BMJ.
Data for the study was obtained from the InterLACE consortium, which provides patient data on reproductive health and chronic diseases. Stroke data was obtained through self-reported questionnaires, hospital and national patient records and death registries.
The researchers hypothesise that the link between infertility and stroke may be through some disorders that can cause infertility. Polycystic ovary syndrome is often associated with higher rates of insulin resistance and glucose intolerance, both of which can increase risk of stroke. Premature ovarian insufficiency, on the other hand, is associated with decreased levels of oestrogen, a potentially neuroprotective and anti-inflammatory hormone. Other studies have shown a higher rate of thyroid autoimmunity, which can further increase the chance of stroke.
Whatever the cause, the authors outlined that stroke is a leading cause of death for women worldwide. Reproductive history could give women clues they are at increased risk before other risk factors such as increased cholesterol become apparent, they said, providing an opportunity to make lifestyle changes earlier.
'GPs need to ask about women's reproductive histories and be aware of recurrent miscarriage and stillbirths as potential predictors of stroke risk,' researchers added.