Many women experience spotting or bleeding, sometimes called metorrhagia, or dysfunctional uterine bleeding, between menstrual periods. Metorrhagia can have benign causes or can signal a serious problem. Bleeding between periods can be caused by hormones, pregnancy, infection or other problems within the reproductive tract. Any type of bleeding between periods should be investigated.
Hormonal Imbalance
Hormone imbalances may lead to metorrhagia, especially in women who are not ovulating. Anovulation, or lack of ovulation, is the most common cause of dysfunctional uterine bleeding, reports Darren Farley, M.D. of the University of Kansas School of Medicine Obstetrics and Gynecology Department. If small amounts of estrogen are being produced, the uterine lining builds up, but since an egg is not ovulated, the normal build up and break down of the lining does not occur. The lining becomes thicker until it starts to slough off, often causing irregular bleeding. Lack of progesterone, which helps prepare the uterine lining for implantation of an embryo, may also cause spotting between periods.
Infections
Infection of the cervix can cause it to be easily irritated and to be bleed easily. Intercourse can cause bleeding from friable, or fragile, cervical tissue. Pelvic inflammatory disease (PID), chlamydia and gonorrhea may also cause bleeding between periods,
Benign Growths
Polyps and fibroids are abnormal benign growths on the uterus that can irritate uterine tissue and make it bleed. Endometriosis, uterine tissue that implants outside the uterus, can also cause metorrhagia.
Cancer
Cancer of the cervix and uterus can cause abnormal bleeding between periods. Less often, vaginal, vulvar or fallopian tube cancers cause metorrhagia, according to Farley. Uterine cancer most often occurs in menopausal women and is more common in women who are obese, because they tend to produce more estrogen, according to the Louisiana State University Health Sciences Center.
Early Pregnancy
Many women experience a small amount of spotting as the embryo implants into the uterus. This usually occurs between six to 12 days after ovulation; spotting may be seen around day 20 to 26 in women with 28-day cycles, since ovulation occurs two weeks before an expected period. Implantation spotting is usually light and scant, lasting only a day or two.
