If pregnancy is a possibility, a pregnancy test is the first step to take when a period is six days late, according to Summit Medical Group. A menstrual period is considered late any time it is more than five days overdue, based on the usual menstrual cycle of a woman. The length of the menstrual cycle varies considerably from woman to woman and can be anywhere from 21 to 35 days.
Only when pregnancy is ruled out should other reasons for the late period be examined, according to Summit Medical Group. One reason that a period can be late is excessive stress, which can include both emotional stress and physical stress. Emotional stress includes relationship problems, family problems and depression, while physical stress includes weight loss, severe illness and excessive exercising.
In rare cases, hormonal imbalance due to problems with the thyroid gland, pituitary gland, adrenal glands or ovaries causes late periods. Call a doctor during regular office hours to schedule an appointment for a late period any time after five days late when there is a chance of pregnancy or if a period does not return for six weeks and there is no chance of pregnancy. Keep track of periods and bring this record to the doctor's office to help take a history and determine the cause of late periods, notes Summit Medical Group.