It's something no one ever wants to see: blood in your underwear — when you're not on your period. Technically, spotting between periods is also known as "intermenstrual bleeding," or metrorrhagia, according to Healthline.
While it can be startling to see for sure, this doesn't necessarily mean anything sinister is going on. There are many reasons why you're spotting between periods.
Some causes are simple to pinpoint such as starting a new medication or contraceptive method. Still, other reasons can indicate a more serious condition, including extreme stress, miscarriage, an infection, diabetes, or even cancer.
Below are seven possible culprits of mid-cycle bleeding.
1. Hormone Fluctuations
Changes in hormones is one major cause of spotting. Since our cycles are controlled by progesterone and estrogen, when the levels of these hormones change, it can lead to spotting between cycles.
Common causes include starting birth control — especially in the first three months, along with thyroid issues or dysfunctional ovaries. If you recently started a new contraceptive and the breakthrough bleeding has been happening for more than three months, check in with your doc.
Unfortunately, the effects of stress aren't limited to just your mental health. Stress can also mess with other areas of our physical health, especially our reproductive systems. Since stress can affect hormone levels, it can also mess up our cycles. (Read more about how stress impacts fertility here.)
3. Certain Medications
Blood thinners, a.k.a. anticoagulants, help keep your blood from clotting. This is a good thing if you are prone to blood clots, but it may also cause you to bleed between periods, Women's Health reports. This study confirms that this anti-coagulant-induced free flow is really a thing. If this sounds familiar, talk to your doctor.
It's good to know that spotting while pregnant doesn't necessarily mean you're miscarrying. It's relatively normal to experience some spotting during the first three months of pregnancy — about 20 percent of women do, according to the American Pregnancy Organization.
However, certain complications during pregnancy can also cause spotting, including miscarriage and an ectopic pregnancy. To be sure, if you're bleeding while pregnant, contact your doctor ASAP.
5. Uterine Fibroids
Fibroids are noncancerous tumors that form in the uterus and can cause bleeding between periods. They can — and should — be treated ASAP, since they could contribute to infertility and other consequences such as cramping, heavy periods, frequent urination, and more.
Spotting between periods may indicate an infection of your reproductive organs, including STIs. Other culprits of inflammatory infections include vaginal douching, intercourse, or pelvic inflammatory disease.
In very rare cases, certain cancers may be the culprit of intermenstrual bleeding, especially cancers that affect the cervix, vagina, uterus, or ovaries.