The majority of women will at some point experience bleeding in the middle of the menstrual cycle. This is called intermenstrual bleeding, or spotting. As with other variations from normal bleeding, sometimes spotting is not something you need to worry about, and other times it can be a sign of a problem.
Spotting mid-cycle can happen for many reasons and is experienced by most women at some point. The most common reason for spotting is due to hormonal birth control. If you have just started a form of hormonal birth control (e.g., the birth control pill, injection, patch, vaginal ring, implant or IUD), spotting is very common in the first few months. If it doesn’t taper off after 3 months, see your doctor. Taking your birth control pill at the same time every day can help prevent mid-cycle bleeding – even a few hours difference can cause spotting, especially for the progesterone-only pill.
Other reasons you might be spotting include:
Some women experience mild spotting during ovulation. This is likely due to hormonal changes related to ovulation. Estrogen causes the endometrium to thicken, and peaks at ovulation. Progesterone rises at that time to maintain the endometrium. If insufficient progesterone is present at the time the estrogen begins to drop, spotting may result. This spotting usually lasts from 1-3 days and is mid-cycle and is not cause for concern.
If your egg was fertilized, it will usually implant in the endometrium about five to seven days later. This may result in light brown or pink spotting as some of the vessels are disturbed when the fertilized egg attaches to the endometrium.
An ectopic pregnancy occurs when a fertilize egg implants in the fallopian tube or elsewhere in your abdomen. This can cause heavy bleeding and pain in your abdomen. An ectopic pregnancy can cause serious complications and must be treated either with medication or surgery.
An infection of your reproductive organs, such as chlamydia or gonorrhea can cause inflammation and bleeding mid-cycle. If you have had unprotected sex with a new partner, or have abnormal discharge or fever, it’s a good idea to get tested.
Cancers or precancerous diseases of the cervix or uterus can cause bleeding between periods. Women between age 25 and 70 should have a Pap smear every three years to screen for cervical cancer. Uterine cancer is more common in post-menopausal women, but if you are experiencing bleeding between periods, see your doctor to rule this out.