Stroke is one of the top causes of death and disability in women around the world. About 3 million women suffered stroke deaths in 2019.
A meta-analysis of observational studies published in The BMJ indicates that infertility and pregnancy loss are associated with an elevated risk of both nonfatal and fatal stroke in later life.
The researchers propose that early screening of women who have had a miscarriage or stillbirth, together with modifications to a healthy lifestyle, could reduce the likelihood of stroke.
Stroke is one of the top causes of death and disability in women around the world. About 3 million women suffered stroke deaths in 2019. Furthermore, women lost 10 million years of healthy living in total due to disability after a stroke, which is 44 percent longer than males.
Women’s greater risk of stroke is not entirely explained by known stroke risks such as obesity, high blood pressure, and diabetes. Previous studies haven’t found a clear link between infertility, miscarriage, and stillbirth and the risk of having a stroke in the long run.
The purpose of this study was to close any existing gaps by examining the relationship between infertility, miscarriage, and stillbirth and the risk of both fatal and non-fatal strokes as well as specific types of stroke.
The researchers examined data from a total of 27 studies from the InterLACE consortium, which compiles information on chronic illness and reproductive health. The research used information from eight studies conducted in seven nations (Australia, China, Japan, Netherlands, Sweden, UK, and the USA).
Information on infertility, miscarriage, and stillbirth was gathered using questionnaires. Using self-reported questionnaires or hospital records, data on nonfatal strokes were also obtained. Hospital records were used to find cases of strokes that ended in death and different kinds of strokes (haemorrhagic or ischaemic).
About 620,000 women between the ages of 32 and 73 took part in the study as a whole.
Of them, 275,863 women had both non-fatal and fatal stroke data, 54,716 only had non-fatal stroke data, and 288,272 only had fatal stroke data. Among them, 4,003 (0.7 percent) had a fatal stroke at a median age of 71, whereas 9,265 (2.8 percent) of the women had their first non-fatal stroke at a median age of 62.
Women having a nonfatal stroke before age 40 were eliminated because they may have suffered a stroke before a history of infertility, miscarriage, or stillbirth could be established. The results were also adjusted for a number of variables, including race, weight, lifestyle, and underlying illnesses.
The study reveals that infertility, miscarriage, and stillbirth are all linked to an elevated risk of stroke, particularly recurrent miscarriages (three or more) and stillbirths.
Women with a history of infertility were 14 percent more likely to suffer a nonfatal stroke than those without a history of infertility.
In addition, miscarriage was associated with an 11 percent increased risk of nonfatal stroke compared to women who had not experienced a miscarriage. The risk went up with the number of miscarriages a woman had: one miscarriage raised the risk of stroke by 7 percent, two miscarriages by 12 percent, and three miscarriages by 35 percent.
The increased risk of non-fatal ischemic and hemorrhagic stroke was 37 percent and 41 percent for women who experienced three or more miscarriages. Similarly, having three or more miscarriages was associated with an 83 percent and 84 percent increase in the risk of fatal ischemic and haemorrhagic stroke.
History of stillbirth was linked to a more than 30 percent increased risk of non-fatal stroke, and women who had two or more stillbirths were over 80 percent more likely to have a non-fatal ischemic stroke.
The study also discovered that having several stillbirths increased the risk of dying from a deadly stroke by more than 40 percent.
According to the research, polycystic ovary syndrome (PCOS) and premature ovarian insufficiency (POI) may be to blame for the association between infertility and increased stroke risk, whereas endothelial dysfunction (narrowing of the heart’s blood vessels) may be to blame for the increased risk of stroke in women who have a history of recurrent stillbirth or miscarriage.
However, studies also imply that poor lifestyle choices (such as smoking or being obese) are linked to miscarriage and infertility, which may potentially increase the risk of stroke.
Since this study is an observational one, can’t establish a cause. Other limitations of the study include the use of questionnaires as the primary data collection method, the lack of sufficient data to investigate the impact of other treatments, and the possibility that various studies have different definitions of infertility, stillbirth, and miscarriage.
However, this was a large, well-designed study, and the results remained mostly unchanged after additional analyses, indicating that the findings are reliable.
“Having a history of recurrent pregnancy loss may be considered as a female-specific risk factor for stroke,” the researchers write.
They also advise that early monitoring of women with a history of miscarriage or infertility, as well as promoting healthy behaviours, may assist to reduce their risk of stroke later in life.
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