China: A study published in Neurology has concluded that a woman's cumulative exposure to estrogen remains protective against stroke after menopause. The researchers have highlighted that lifetime cumulative estrogen exposure due to reproductive factors acts as an early warning indicator for stroke and its subtypes.
It is already known that multiple reproductive factors are tied to stroke. However, there needs to be more data on the cumulative effects of reproductive factors on stroke and the subtypes among Chinese females during the reproductive life course.

Considering this background, researchers assessed the association between lifetime cumulative estrogen and stroke among postmenopausal Chinese women.
The study summary includes the following:
From the CKB study (China Kadoorie Biobank), postmenopausal females were selected without prior history of stroke at baseline (2004-2008) with a total of 122,939 postmenopausal women aged 40 to 79 years.
Three composite indicators were used to assess Lifetime cumulative estrogen exposure due to reproductive factors, namely reproductive lifespan (RLS), endogenous estrogen exposure (EEE), and total estrogen exposure (TEE).
Stroke and its subtypes, namely ischemic stroke (IS), intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH), were identified (2004-2015).
The median follow-up was 8.9 years.
The researchers identified 15,139 new-onset stroke cases.
There were 12,853 cases of ischemic stroke, 2,580 intracerebral hemorrhage and 269 cases of Subarachnoid haemorrhage.
Compared with Q1 (lowest quartile) of Reproductive Life Span, the highest quartile (Q4) had a lower total stroke risk having aHR of 0.95.
The adjusted HR for total estrogen exposure was 0.87
The adjusted HR for Endogenous Estrogen Exposure was 0.85
To conclude, estrogen level decline during the postmenopausal period. Exposure to estrogen throughout life is a valuable indicator to determine the risk of stroke and its type after menopause.
Further reading:
Lifetime Cumulative Effect of Reproductive Factors on Stroke and Its Subtypes in Postmenopausal Chinese: A Prospective Cohort Study Leying Hou, Shuting Li, Siyu Zhu, Qian Yi, Wen Liu, You Wu, Feitong Wu, Yuelong Ji, Peige Song, Kazem Rahimi Neurology Feb 2023, 10.1212/WNL.0000000000206863; DOI: 10.1212/WNL.0000000000206863