Introduction

Stroke is not just a medical concern but a global epidemic, contributing significantly to morbidity and mortality worldwide. In 2019 alone, there were approximately 101 million stroke cases globally, with stroke accounting for 11.6% of all deaths [1]. In China, the numbers are staggering, with about 24.18 million cases of ischemic stroke and 5.94 million cases of hemorrhagic stroke, presenting a profound challenge for public health and the healthcare system [2].

While stroke affects both men and women, significant differences exist in how each gender experiences its prevention, treatment, and outcomes. Studies show that women, particularly as they age, face a heightened risk and more severe consequences from stroke compared to their male counterparts [3, 4].

Traditionally, stroke risk factors have focused on typical contributors like hypertension and diabetes. However, sex-specific factors, particularly those associated with reproductive health, have shown to disproportionately affect women throughout their lives [3]. Key stages such as menarche, pregnancy, breastfeeding, and menopause play vital roles in the development of cardiovascular issues, including stroke [5, 6]. For instance, early menopause and high parity (the number of times a woman has given birth) have been linked to an elevated risk of ischemic stroke [8, 9]. The timing and number of children a woman bears also significantly impacts stroke development [10], while adverse pregnancy outcomes like stillbirth have been correlated with higher stroke risks [11, 12]. Despite these insights, the overall impact of these reproductive events on stroke remains poorly understood.

Adding to the complexity is the role of socioeconomic status (SES), which can amplify the relationship between reproductive factors and stroke risk. SES, encompassing income, employment, and education, has been shown to modify this association through various mechanisms, such as influencing healthcare access, health behaviors, and exposure to risk [13, 14, 15]. Understanding how these reproductive profiles affect women across different socioeconomic backgrounds is critical in developing effective cardiovascular prevention strategies.

Study Overview

A groundbreaking study based on the China Kadoorie Biobank (CKB) aims to investigate the connections between stroke and reproductive factors among postmenopausal women, particularly looking at variations based on SES. The CKB study began recruiting participants aged 30-79 from diverse regions of China between June 2004 and July 2008, ultimately including 138,873 eligible postmenopausal women after careful selection.

Key Findings and Data Highlights

1. **Reproductive Factors**: Data collected included variables such as age at menarche, menopause, number of live births, stillbirths, and miscarriages. Seven key reproductive risk factors were analyzed, showing significant associations with both total stroke and its subtypes [22].

2. **Incidence and Risk**: By the end of the study period in December 2015, 17,042 of the participants developed stroke, with distinctions among subtypes: ischemic, intracerebral hemorrhage, and subarachnoid hemorrhage. Certain reproductive factors were tied to increased stroke risks, revealing that: - Early age at menarche was associated with a hazard ratio (HR) of 1.05 for total stroke. - High parity showed an even greater risk, with an HR of 1.18 for total stroke. - Notably, women with no history of lactation faced a staggering HR of 1.33 regarding stroke risk [table 2].

3. **Socioeconomic Disparities**: The study identified distinct variations in the impact of reproductive factors across different socioeconomic classes. High parity significantly increased stroke risk among low-SES women, while high-SES women were more affected by no history of lactation. Women from lower SES backgrounds showed a higher prevalence of reproductive risk factors, which may contribute to their disproportionate stroke burden.

4. **Population Attributable Fractions (PAFs)**: The PAF calculations indicated that reproductive factors accounted for a substantial portion of stroke cases—9.0% attributable to high parity alone in the total population. When analyzing different socioeconomic classes, low-SES women experienced a higher collective risk from their reproductive health profiles compared to high-SES women, who showed lower combined PAFs from the same factors [additional data].

5. **Health Implications**: The findings emphasize the urgency of addressing socioeconomic disparities in healthcare. Women with lower socioeconomic status may lack access to the necessary preventive measures and education, perpetuating the cycle of health inequities. Effective interventions must incorporate reproductive healthcare tailored to women’s unique experiences and needs.

Conclusion

This pioneering research sheds light on the pressing need to consider reproductive health as an essential factor in stroke risk assessments. As stroke remains one of the leading health threats to women globally, a focused approach considering both reproductive histories and socioeconomic contexts could pave the way for more equitable health strategies, particularly for vulnerable populations.

Understanding these dynamics is vital for stakeholders to create targeted healthcare policies and programs that can positively impact women’s health across diverse socioeconomic backgrounds. By fostering greater awareness and implementing informed interventions, we can collectively work toward reducing stroke incidences and improving outcomes for women everywhere.