From the first menstrual period through the onset of menopause, women occasionally experience vaginal bleeding or spotting at unexpected, random times. While many of these irregularities are no cause for concern, the numerous "what-ifs" that accompany premenstrual spotting can leave a woman feeling uncertain. Brown spotting before a period can occur due to a change in cycle length, birth control usage, ovulation, hormonal changes, infection, injury or other disease-related causes.
Perhaps the most common explanation for spotting before a period is an irregular cycle, meaning one in which the complex coordination of hormone balance is slightly askew. These irregularities are relatively common and typically lead to failure to ovulate, or release a mature egg from the ovary. When an egg isn't released, the menstrual hormones become temporarily imbalanced. This often leads to spotting before the normal vaginal bleeding of a period begins. Irregular cycles in which ovulation fails to occur are common early and late in a woman's childbearing years, but they can also occur due to stress, illness, extreme dieting and other temporary situations.
Certain types of birth control commonly lead to spotting and irregular bleeding. This occurs frequently in women using a copper intrauterine device and hormonal birth control that includes only a progesteronelike hormone without estrogen -- including so-called mini pills, depot shots (Depo-Provera) and the birth control implant (Implanon). Less commonly, combination birth control containing both estrogenlike and progesteronelike hormones, including pills, vaginal rings and patches, can also sometimes cause pre-period spotting. Irregular bleeding and spotting is generally most likely within the first 3 months of use. Spotting is also more likely if pills are not taken at the same time daily or doses are missed or not taken as prescribed.
Injury and Infection
The uterine opening at the top of the vagina, or cervix, can bleed a small amount if touched or manipulated. Some women are more prone to this than others are. Minor injury to the cervix, resulting from things as innocuous as aggressive intercourse or a Pap test, can result in brown or bloody discharge as soon as the same day or as late as a few days after the incident.
Infections of the reproductive organs -- caused by sexually transmitted infections like chlamydia and gonorrhea or bacterial vaginosis, for example -- can also cause unexpected bleeding, which might occur anytime during the menstrual cycle.
Ovulation and Pregnancy
For some women, a small amount of bleeding happens simultaneously with ovulation, which occurs about halfway through a regular menstrual cycle. This might be accompanied by midcycle, one-sided pain followed by spotting.
In the earliest stage of pregnancy, about a week after ovulation, a fertilized egg embeds into the uterine wall. This process can result in implantation bleeding that appears as vaginal spotting. Though bright red blood is more commonly associated with this event, it is possible that brown vaginal discharge can be a very early indication of pregnancy.
Bleeding from outside a woman's reproductive tract, such as lower intestinal bleeding or hemorrhoids, might be mistaken for premenstrual spotting. Uterine, cervical or ovarian cancer, fibroids, uterine polyps and endometriosis -- when the uterine lining grows outside of the uterus -- are other possible causes of spotting and irregular bleeding. Bleeding disorders and endocrine conditions, such as polycystic ovary syndrome or thyroid disease, could also be responsible. Further, as women approach menopause, periods tend to become increasingly heavier and more frequent, which could explain atypical bleeding.
Warnings and Next Steps
In general, isolated spotting indicates no immediate health concern. However, if spotting is frequent, accompanied by pain or other symptoms, or continues for more than 3 months after beginning a birth control regimen, it’s important to contact your doctor to rule out a more serious problem. Seek emergency medical attention if spotting progresses to heavy bleeding such that you’re saturating a pad or tampon more often than every 1 to 2 hours, if associated pain becomes severe, or if you pass large blood clots or feel dizzy as these symptoms might signal a potentially dangerous condition.