The typical woman's period begins in puberty and ends at the onset of menopause. Both of these occurrences are controlled by hormones, which also control the length and regularity of a woman's period throughout the lifetime of menstruation. Thus, the most common causes of irregular periods are linked to differing fluctuations in hormones, though other factors such as stress, diet, or some medical conditions can also have an impact. Periods are considered irregular when they do not occur on a consistent schedule or fall outside of what is considered to be the average range determined by medical professionals.
Periods commonly occur about every 23-35 days. Many women only get their periods a few times a year, however, and others may get their periods a few times a month. This isn't usually cause for alarm because what is regular for one woman many not be regular for another. It is always a good idea to discuss concerns about irregular periods with one's physician, because it is important to go over the possible causes of irregular periods to ensure one is not at risk for a health issue.
The most common times for a period to be irregular are at the onset of the period during puberty, and at the end of the period when menopause begins. At these times the body is adjusting to the changes in hormones that control the start and stop of menstruation. Irregular periods at those times is simply the result of the body's adjustment to the new hormone fluctuations. Stress is another common reason for irregular periods. When the body is stressed, regardless of whether or not it is physical, mental, or emotional stress, the response is to produce a hormone called cortisol. This hormone, in turn, may affect estrogen, progesterone, and DHEA, all of which play a role in menstruation.
Other common causes of irregular periods are excessive exercise, eating disorders, and illness. Though most causes are not harmful, eating disorders and illness are causes of irregular periods that should be addressed by a doctor. Two health issues associated with irregular periods are polycystic ovarian syndrome and uterine abnormalities such as endometriosis. Polycystic ovarian disorder is a leading cause of infertility, and endometriosis can also affect fertility as well as cause very painful periods. Women should track their cycles and let their doctor know when large variances occur so they can ensure that illness is not the cause.
