A normal menstrual period occurs every 21 to 32 days and will last between four and seven days. Unfortunately some women experience breakthrough bleeding, or spotting, between their normal periods. This spotting can last for a couple of hours to a couple of days depending upon the reason behind the condition.
Whether it’s the first time you’re experiencing irregular bleeding between periods or just another month of spotting it can be frustrating and lead to concerns about what is wrong. While there may be several more common reasons for breakthrough bleeding or spotting to occur it is important for women to seek the advice of their gynecologists or primary care physician in order to rule out reasons which may be more dangerous. (1)
For some women their first thought is that they have developed uterine cancer. When the uterus has something wrong the only thing it can do is to bleed and when there is a cancerous growth there is usually spotting or breakthrough bleeding between periods. However, uterine cancer is more rare than other more common occurrences which increase the risk for spotting between periods.
For most women however there is a more simple explanation. Menstrual periods are controlled by hormonal surges in the body and these hormonal surges are influenced by the amount of stress a woman is experiencing at any specific time during her day or month. Stress is a common cause of breakthrough bleeding or spotting.
Sexually transmitted diseases or infections are another reason women may experience spotting or breakthrough bleeding. Women who had intrauterine contraceptive devices are also at greater risk for a uterine infection or irritation of the uterus that will cause spotting. (2,3)
Some women may have abnormalities of the cervix or uterus that can cause unusual bleeding. The gynecologist will take a cervical smear and arrange for a pelvic ultrasound examination to determine if there are any structural abnormalities that are causing breakthrough bleeding.
Women who have fibroid tumors may also experience breakthrough bleeding. Fibroid tumors are benign tumors that can range from the size of a dime to the size of a small soccer ball. These tumors are filled with blood and tissue and, on occasion, parts of the tumor die and are sloughed off in the middle of the month. (4)
Women who have fibroid tumors may experience menstrual cramping or pelvic pain, both during their menstrual period or during sexual intercourse.
Some women can experience breakthrough bleeding in the middle of the month if she has a low progesterone level which controls the build-up of endometrial tissue in the uterus.
Spontaneous abortions can also cause breakthrough bleeding or spotting in the middle of the month as well as hormonal fluctuations or starting and stopping or missing oral contraceptive pills. Some women who have low thyroid levels will experience spotting because the thyroid hormone has a role in the hormonal control of the reproductive system. (4)
For the most part vaginal infections will cause symptoms but in some women they will go undiagnosed. These undiagnosed vaginal infections can cause bleeding from the vagina as opposed to from the uterus but will mimic spotting in the middle of the month.
Certain drugs that a woman takes will also cause breakthrough bleeding such as anticoagulant therapy. And some women who undergo GYN procedures will experience spotting.
Women should keep a menstrual calendar to show their physicians who can use this information to help determine an accurate diagnosis and therefore a successful treatment protocol.
(1) NHS Choices: What Causes Bleeding Between Periods?
(2) MayoClinic.com: Mirena (Hormonal IUD)
(3) MayoClinic.com: ParaGard (Copper IUD)
(4) American Association of Family Physicians: Abnormal Uterine Bleeding