According to the National Institutes of Health, any variation to a normal menstrual cycle is considered an irregular period, or oligomenorrhea. NIH defines a normal period as lasting four days in a 24 to 34 day cycle; however, the length of the cycle can be as short as 21 days and as long as 45 days in young teenage women. Irregular periods affect around 30 percent of women who are in their reproductive years, according to Epigee Women's Health.
Period Timing
If a woman's period occurs at an abnormal time, it can be considered an irregular period, according to Epigee. Abnormal period timing includes an early period, which occurs before 21 days in the cycle, or a late period, which occurs after 45 days in the cycle. In addition, women might have two periods that occur within her menstrual cycle, or a continuous period where a second period starts at the end of the first period.
Abnormal Bleeding
According to NIH, extremely heavy bleeding, or menorrhagia, is a symptom of an irregular period. For example, if a woman soaks her menstrual pad or tampon every two to three hours, it is considered a heavy period. On the opposite spectrum, scanty bleeding is also a symptom of an irregular period. Instead of a regular flow, the woman will have spotting, or a blood flow that starts, then stops soon after.
Missed Period
Another sign of an irregular period is a missed period, according to Epigee. Termed amenorrhea, it is considered a missed period when a woman does not have her period for 90 days, or has not started menstruating by the age of 15. However, Epigee recommends using a pregnancy test to determine whether the missed period is due to a pregnancy. In addition, post pill amenorrhea can occur when a woman stops using hormone-based birth control.
