Aspirin is used to prevent ischemic stroke and other types of cardiovascular disease. Seven trials of aspirin focusing on the effectiveness of primary prevention of stroke and other cardiovascular events have been performed, but three of these did not include women. Data from these trials, and one meta-analysis, suggest that aspirin prevents myocardial infarction in men and stroke in women, although the findings in women were driven by the results of a single large study, and a subsequent meta-analysis did not find a gender difference. The reasons for the possible gender differences in aspirin's effectiveness are not entirely clear.