The association between cumulative estrogen exposure, parity, and stroke occurrence
Stroke is caused by an interference to the brain's blood supply due to a bleeding or a clot, that results in brain tissue damage or death. Stroke can impair thinking, speaking and moving. It is the leading cause of disabilities in adults worldwide and the 4th most common cause of death. There are known differences between men and women in stroke risk-factors, occurrence, and in short and long-term outcomes. In women, there is an increased risk for stroke during pregnancy and following delivery. These periods are characterized by many physiological changes, including dramatic changes in sex hormone levels. Other risk factors in women, including use of oral contraceptives and hormone replacement therapy, led to the assumption that sex hormones could play a role in stroke risk. Several previous studies suggested that multiple pregnancies and the changes in hormone levels have an accumulating long-term effect on stroke risk. However, other studies did not find this relationship. In addition, it is possible that other changes that are associated with parenting but not with pregnancy, such as reduction in sleep and physical activity, and an increase in stress levels, contribute to the risk for stroke.
In our study we aim to investigate the relationship between the number of pregnancies and stroke in women, while accounting for other risk factors. We will also investigate the effect of the estimated life-time exposure to estrogen, a sex hormone that is thought to have a protective effect from stroke risk. Since parenting is associated with many changes to life-style, we want to investigate the effect of the number of children in men as well, to separate the physiological impact of pregnancy from the effects of life-changes due to parenting.
The large dataset of the UK BioBank will allow us to answer these questions, and improve our understanding of the relationship between pregnancies, sex-hormone exposure and parenting, to stroke risk. The results of this study will improve our ability to identify population that are at increased risk for stroke, and offer preventive intervention such as diet changes and increased physical activity, as well as closer monitor of other risk factors such as high blood pressure and high levels of lipids, to help minimize the risk for stroke