What Are the Causes of Mid-Cycle Spotting?

According to Target-Woman.com, mid-cycle spotting can occur through the vagina, perineum or cervix. It typically occurs between 10 to 16 days after a woman's previous menstrual period and lasts between 12 and 72 hours. The flow of blood is very light and pink, red or rust brown in color. Approximately 30 percent of women experience mid-cycle spotting at some point during their menstruating years, and the occurrence is considered perfectly normal unless caused by cancer or other serious conditions.

Ovulation

• According to Beyond-Fertility.com, spotting during ovulation can be an excellent sign of fertility. Occasionally mid-cycle spotting due to ovulation is accompanied by slight pain on whichever side of the lower abdomen houses the egg-releasing ovary. Spotting typically lasts two to three hours, but can last between one two days in some cases. Bleeding during ovulation can be caused by the temporary reduction in estrogen production, causing the endometrium to shrink and bleed; some scientists believe mid-ovulation bleeding can stem from the cervix, which also shrinks due to a lack of estrogen, or from the ovaries as they release eggs for fertilization.

Pregnancy

• Pregnancy can cause mid-cycle spotting. When a fertilized egg burrows its way in the lining of the uterus, it can cause spotting that lasts between 24 to 48 hours. This process is called implantation; it often occurs before women are aware of their pregnancy and can be mistaken for the beginnings of a menstrual period.

Hormones

• Fluctuation in hormones is another frequent cause of mid-cycle bleeding. The hormone progesterone helps prepare the uterine lining for pregnancy; when fertilization does not occur, the progesterone level falls and occasionally causes spotting. This drop in progesterone has also been linked to early miscarriage and minor infertility. High insulin levels and/or low thyroid function can also cause mid-cycle spotting, as they affect estrogen and progesterone levels.

Uterine Fibroid Tumors

• Uterine fibroids, although typically harmless, can cause mid-cycle spotting. Uterine fibroids are benign tumors that occur in the uterus, and are usually round or semi-round. Although the exact cause of uterine fibroids is not know, scientists have observed that they are more likely to occur in women with a a family history of fibroids. According to Medicine-Net.com, women with African ancestry are diagnosed with uterine fibroids two to three times more often than women of other races. Oral birth control and pregnancy may decrease the chances of fibroid tumors. Beer consumption, hypertension, beginning menstruation before 10 years of age and uterine infections can increase the likelihood of developing fibroids.

Birth Control

• Oral contraceptives and IUDs (Intra-uterine devices) can also cause mid-cycle spotting in some women, as they cause a fluctuation in hormone levels. In the case of oral contraceptives, mid-cycle spotting is more likely to occur if the pills are not taken at the same time every day or within the first few months of beginning use of birth control.

Cancer and Serious Conditions

• Although rare, serious health conditions can cause mid-cycle spotting. These include cervical polyps; infection of the vagina, cervix or uterus; cervical erosion; ovarian cysts; or foreign objects in the vagina or cervix, such as a tampon or birth control. Certain cancers may also cause mid-cycle bleeding, such as uterine or cervical cancer.