Irregular periods are generally not cause for alarm, but in some instances may signify an underlying medical problem, according to EverydayHealth. As many as 30 percent of women during childbearing years have irregular periods.
Periods that occur more often than every 21 days or that last for more than 8 days are considered irregular. Late, early or missed cycles are also classified as irregular.
Irregular periods are many times caused by anovulation, which is a condition that occurs due to hormonal imbalances and causes ovulation to fail to take place. Severe or even subtle hormone imbalances can cause a variation in the monthly cycle, usually due to medical conditions or lifestyle choices.
Extreme dieting or exercise can cause irregularity in periods, and anxiety, including both short-term and chronic conditions, can cause hormonal imbalances and irregular cycles.
The use of birth control pills can also cause both more frequent periods, fewer periods, or even cause a woman to not have a period. Polycystic ovarian syndrome, or PCOS, can also cause irregular bleeding, as can thyroid problems, diabetes, eating disorders, fibroids, endometriosis and sexually transmitted diseases, notes EverydayHealth.
Women who experience consistently irregular periods should be evaluated by a medical professional.