Hi, thank you for query, If you are not pregnant, other causes of missed or irregular periods include: Excessive weight loss or gain. Although low body weight is a common cause of missed or irregular periods, obesity also can cause menstrual problems. Eating disorders, such as anorexia or bulimia. For more information, see the topic Anorexia Nervosa or Bulimia Nervosa. Increased exercise. Missed periods are common in endurance athletes. Emotional stress. Illness. Travel. Medicines such as birth control methods, which may cause lighter, less frequent, more frequent, or skipped periods or no periods at all. Hormone problems. This may cause a change in the levels of the hormones that the body needs to support menstruation. Illegal drug use. Problems with the pelvic organs , such as imperforate hymen, polycystic ovary syndrome, or Asherman s syndrome. Breast-feeding. Many women do not resume regular periods until they have completed breast-feeding. Remember, you can still become pregnant even though you are not menstruating. Practice birth control if you do not wish to become pregnant. Premature ovarian failure is when you stop menstruating before age 40. Surgery, chemotherapy, and radiation therapy to the abdomen or pelvis may cause premature ovarian failure. Other diseases such as irritable bowel syndrome, tuberculosis, liver disease, and diabetes can cause missed or irregular periods, although this is rare. But if any of these diseases are present, you will usually have other symptoms besides menstrual irregularities. If you ve skipped a period, try to relax. Restoring your life to emotional and physical balance can help. Many women miss periods now and then. Unless you are pregnant, chances are your cycle will return to normal next month. Check your symptoms to decide if and when you should see a doctor.