Hormonal changes that occur as a result of changing birth control pills, perimenopause or problem pregnancies can often cause excessive menstrual bleeding, according to the New York Times. Bleeding for longer than one week is considered abnormal menstrual bleeding and is reason to be seen by a gynecologist, states the New York Times.
The amount of blood flow is also a consideration in menstrual bleeding, as a heavy period for a week with mild spotting for a subsequent week is not cause for concern, while two weeks of heavy bleeding definitely warrants a trip to the gynecologist, according to Kotex. Any number of lifestyle factors, including stress, diet, travel, illness, weight loss or weight gain, can also account for changes in the menstrual cycle, according to the New York Times.
Both healthy pregnancies and ectopic pregnancies can result in bleeding in excess of one week, making it important to consider pregnancy as an option when possible, according to Kotex and the New York Times.
Perimenopause, or the initial change before menopause, can cause bleeding in excess of two weeks, as well as periods that occur more frequently, according to Ladies Home Journal. While not as common, two week-long periods can be a sign of a more serious condition, such as uterine cancer, thyroid and pituitary disorders, uterine fibroids or uterine infection, according to the New York Times.