The study found that women who enter menopause early or do not use hormone replacement therapy may have a higher risk of stroke.
And women who had longer reproductive lives and used birth control or HRT had fewer strokes by the mid-60s.
According to experts, the findings suggest that women who go through menopause early should have their blood pressure and cholesterol levels checked more regularly.
The researchers used data from nearly 123,000 postmenopausal women with an average age of 58 years.
They were asked about their lifestyle, as well as information about their reproductive health, such as age at first menstruation and menopause, number of pregnancies and abortions, and use of oral contraceptives.
The researchers then used health insurance and disease registry data to identify participants who had a stroke in the next decade.
Some of them, 15,139, had a stroke, 12,853 had an ischemic stroke in which blood flow to the brain is blocked, 2,580 had an intracerebral hemorrhage, and 269 had a subarachnoid hemorrhage, a hemorrhage between the brain and the membrane that covers it.
They were then divided into four groups based on their reproductive period and the number of years from first menstruation to menopause. Women with the shortest reproductive lifespan are known to have had up to 31 reproductive years, compared to 36 years or more in the longer group.
When the researchers adjusted for other factors that may have affected stroke risk, such as age, smoking, physical activity and high blood pressure, they found that the higher group had a 5% lower risk of all types of stroke.
The rate rose to 13 percent for intracerebral hemorrhage compared with the shortest group, according to results published in the journal Neurology.
The researchers also looked at other factors that affect estrogen levels, such as the number of births and oral contraceptive use, both of which are associated with higher levels.
They found that higher estrogen levels lead to a reduced risk of all types of strokes, as well as ischemic stroke and intracerebral hemorrhage.
Lead author Paige Song of the Zhejiang University College of Medicine in Hangzhou, China, said the results show that lifetime exposure to estrogen may be a useful predictor of stroke risk in postmenopausal women.
She said: “Our study shows that higher estrogen levels due to a number of reproductive factors, including longer reproductive age and use of hormone therapy or birth control, are associated with a lower risk of stroke and intracerebral hemorrhage. These results may provide new insights for stroke prevention.” For example, consider screening people with short-term exposure to estrogen.”
Source: Daily Mail