Summary: A long-term community study suggests that women who have three or more live births face a lower risk of stroke and of hidden vascular brain damage. These results point to an overlooked reproductive factor that could improve stroke risk assessment for women.
Researchers analyzed data from the Framingham Heart Study and found that having three or more live births was linked with a substantially lower incidence of all-cause stroke and with fewer MRI signs of vascular brain injury, such as covert brain infarcts and reduced white matter hyperintensity volume. Given that women represent a majority of stroke cases in the United States, identifying female-specific predictors of risk has clear clinical importance.
Key Findings
- Three or more live births lowered stroke risk: In an analysis of 1,882 women followed for a median of 18 years, those with three or more live births had a significantly reduced risk of all-cause stroke compared with women who had no live births.
- Fewer covert brain injuries: Women with three or more live births also showed a reduced prevalence of covert brain infarcts and lower white matter hyperintensity volumes on MRI—both markers of small-vessel vascular brain damage.
- Distinct predictive value: Other reproductive measures evaluated in the cohort—such as age at menopause, use of postmenopausal hormone therapy, and measured estradiol or estrone levels—did not show the same consistent protective association, highlighting number of live births as a distinct predictor in this sample.
- Robust after adjustment: Associations remained statistically significant after controlling for standard vascular risk factors, including hypertension and cholesterol.
Study background
Stroke remains a leading cause of disability and death, and it affects women disproportionately; women account for a majority of stroke cases in the U.S. Reproductive history influences lifetime exposure to endogenous estrogen and other physiological states, and these factors have been proposed as modifiers of cerebrovascular risk. However, prior evidence about whether live births influence later stroke risk has been inconsistent.
Study design and participants
This prospective cohort study included 1,882 women from the Framingham Heart Study Offspring cohort who were stroke-free at baseline (1998–2001) and had a mean age of about 61 years. Investigators recorded reproductive variables—including number of live births, age at menopause, postmenopausal hormone therapy use, and serum estradiol and estrone—and followed participants for incident all-cause stroke over a median 18-year period. Cross-sectional MRI outcomes included covert brain infarcts and white matter hyperintensity volume as markers of vascular brain injury.
Results
During follow-up, 126 women experienced a stroke. In multivariable Cox proportional hazards models that adjusted for vascular risk factors, having three or more live births (compared with zero) was associated with roughly half the risk of stroke (hazard ratio approximately 0.51). Cross-sectional analyses of MRI data similarly showed that women with three or more live births had lower odds of covert brain infarcts and smaller white matter hyperintensity burden. No consistent associations were observed between other reproductive factors and either clinical stroke or MRI markers of vascular injury in this cohort.
Implications
The authors suggest that number of live births could be considered as an additional female-specific variable in clinical tools that predict stroke risk. While the findings point to a measurable association between reproductive history and later cerebrovascular health, they do not imply that childbirth alone determines stroke risk. Lifestyle factors such as diet, exercise, and genetics remain central to prevention, and further work is needed to confirm these results in other populations and to clarify biological mechanisms.
Key Questions Answered:
A: The study suggests pregnancy-related biological changes and hormonal exposures may confer some vascular protection, but pregnancy is only one of many factors that influence long-term brain health.
A: Not necessarily. The observed reduction in risk for women with three or more live births is statistically significant in this cohort, but it does not mean women with fewer or no children are destined to have strokes. Individual risk depends on many variables.
A: Estrogen has been characterized as neuroprotective in some studies: it can support vascular elasticity, modulate inflammation, and influence cerebral blood flow. Longer lifetime exposure to endogenous estrogen has been linked in other work to lower markers of small-vessel disease in women.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The original journal paper was reviewed in full.
- Additional context was provided by editorial staff.
About this neurology research news
Author: Steven Lee
Source: UT San Antonio
Contact: Steven Lee – UT San Antonio
Image: The image is credited to Neuroscience News
Original Research: Open access. “Number of Live Births as a Protective Factor Against Clinical and Covert Brain Infarcts: The Framingham Heart Study” by Senan Maher et al., published in the Journal of the American Heart Association. DOI: 10.1161/JAHA.125.044037
Abstract
Number of Live Births as a Protective Factor Against Clinical and Covert Brain Infarcts: The Framingham Heart Study
Background
Female-specific reproductive factors have been linked to stroke risk, but evidence for some factors—such as the number of live births—has been mixed. This study evaluated how number of live births and other reproductive characteristics relate to later risk of clinical stroke and MRI markers of vascular brain injury in a community cohort.
Methods
A prospective analysis included 1,882 women (mean age 61.3 years) from the Framingham Offspring cohort who were stroke-free at baseline (1998–2001). Reproductive factors examined were number of live births, age at menopause, postmenopausal hormone therapy use, and serum estradiol and estrone. The primary outcome was incident all-cause stroke; secondary outcomes were covert brain infarcts and white matter hyperintensity volume on MRI.
Results
Over a median 18-year follow-up, 126 women had a stroke. After adjusting for vascular risk factors, having three or more live births versus none was associated with a lower risk of stroke (hazard ratio ~0.51). Cross-sectional MRI analyses showed fewer covert brain infarcts and lower white matter hyperintensity volume among women with three or more live births. Other reproductive variables were not significantly associated with outcomes in this sample.
Conclusions
A higher number of live births was associated with reduced risk of stroke and covert brain infarcts in this community-based cohort. Number of live births may warrant consideration in female-specific stroke risk prediction, though additional studies are needed to validate and understand these associations.