Definition: A menstrual cycle that is different in some way than your typical, normal period. This may mean that your period lasts longer or is shorter or that it comes earlier or later than anticipated. It may be a difference in the amount of flow. Any of these variances may indicate that you are pregnant. This could be that you've thought of bleeding as a period, when it was really implantation bleeding.
Examples:An abnormal period may be a sign of pregnancy.