A study found that women who enter menopause early or who do not use hormone replacement therapy may have a higher risk of stroke.
And women who had a longer reproductive life and used contraceptives or HRT had fewer strokes by their mid-60s.
Experts said the findings suggest that women who start menopause early should have their blood pressure and cholesterol checked more regularly.
The researchers used data from nearly 123,000 postmenopausal women, with an average age of 58.
They were asked about their lifestyle as well as information about their reproductive health, such as age at first menstruation and onset of 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, with 12,853 having an ischemic stroke – where blood flow to the brain is blocked – and 2,580 had intracerebral hemorrhages, and 269 had subarachnoid hemorrhage, bleeding between the brain and the membrane that covers it.
They were then divided into four groups determined by their reproductive period and the number of years from the first menstrual period to menopause. Women with the shortest reproductive lifespan were known to have had up to 31 reproductive years, compared to 36 or more years in the longer group.
When the researchers adjusted for other factors that could influence stroke risk, such as age, smoking, physical activity and high blood pressure, they found that participants in the taller group had a 5 percent lower risk of all types of stroke.
This rose to 13 percent with intracerebral hemorrhage compared to the shortest group, according to findings published in the journal Neurology.
The researchers also looked at other factors that influence estrogen levels, such as the number of births and use of oral contraceptives, both of which are associated with higher levels.
They found that higher estrogen levels led to a lower risk of all types of strokes, as well as ischemic stroke and intracerebral hemorrhage.
Lead author Paige Song, of Zhejiang University College of Medicine in Hangzhou, China, said the findings show that lifetime exposure to estrogen can be a useful predictor of stroke risk in postmenopausal females.
She said: “Our study suggests that higher estrogen levels due to a number of reproductive factors, including longer reproductive age and use of hormonal therapy or contraceptives, are associated with a lower risk of stroke and intracerebral hemorrhage. These findings may inform new ideas for stroke prevention.” Like considering screening people with short-term exposure to estrogen.”