Bleeding Between Periods - Causes

Bleeding or spotting between periods is something that lots of women experience at some point, either occasionally or regularly, during every menstrual cycle. It is important to acknowledge any non-menstrual bleeding or spotting, as it can indicate medical problems that require treatment. 

Normal menstrual cycles can last anywhere from 21 to 35 days. Most women have irregular cycles at the beginning and end of their reproductive lives, while some will always remain irregular. Menstrual flow itself also varies from woman to woman and sometimes from month to month — a woman may bleed for as little as three days or as long as a full week. 

"Mid-cycle bleeding" doesn't have to occur right in the middle of your cycle, and unless there is an obvious explanation such as ovulation or implantation bleeding, it should always lead a woman to make an appointment with her obstetrician/gynecologist. 

In this article, we'll take a look at possible causes of bleeding or spotting between periods, as well as the other symptoms associated with these causes. 

Ovulation Bleeding And Implantation Bleeding

Some women regularly experience a light spotting that is easy to miss around the time of ovulation. This is due to hormonal changes. More concretely, because the uterine lining has thickened in preparation for a possible pregnancy but the hormone progesterone has not reached a level at which it can easily be contained. The cervix opens as you approach ovulation, which makes it easier for blood to be expelled. This bleeding is called ovulation bleeding.

Another benign cause of bleeding during your menstrual cycle is an implantation bleeding. If you are trying to conceive and notice a light spotting between seven and 10 days following ovulation, it could be a very early pregnancy sign. An implantation bleeding is created as a tiny embryo implants into the blood-rich environment of the uterine lining. Around 20 percent of women experience this light spotting when they get pregnant.

Uterine Fibroids And Polyps

Uterine fibroids are non-cancerous growths within the uterus, that affect many women of reproductive age at some point. Fibroids develop from the smooth muscular tissue of the uterus, and they can be so small that you'd need a microscope to detect one or so large that they affect the shape of the uterus. 

Fibroids can result in heavy and prolonged menstrual periods, pain (in your back and legs as well as obviously your abdomen), frequent urination and constipation as well as irregular bleeding.

Uterine polyps are often confused with fibroids, but they form differently. They are attached to the inner wall of the uterus, and form from the overgrowth of endometrial (uterine lining) tissue. Like fibroids, polyps vary greatly in size. 

Irregular menstrual bleeding, heavy bleeding, and infertility can result in addition to bleeding between periods. Polyps are more common in older women who are approaching the menopause. 

Adenomyosis 

Adenomyosis is a disorder of the endometrium, the tissue that usually lines the uterus. Less well-known then endometriosis — in which endometrial tissue appears outside the uterus — 

Adenomyosis is more common in the later stages of the reproductive years, after having children. Besides bleeding between periods, symptoms include heavy and prolonged periods, heavy pain and cramps, passing blood clots and pain during intercourse.

Cervical, Endometrial, And Ovarian Cancer

The possibility that abnormal vaginal bleeding is an indication of cancer is the reason it is always wise to see a doctor if you notice bleeding between periods or after the menopause. 

Cervical cancer typically does not have symptoms in the early stages. When symptoms appear, the cancer is already more advance. Vaginal bleeding, watery discharge that can smell foul and contains blood, and pelvic pain (including during sexual intercourse) would be tell-tale signs.

Endometrial cancer causes abnormal vaginal bleeding in its earlier stages, something that facilitates early detection. The  remaining symptoms are the same as described for cervical cancer. 

Ovarian cancerstarts in the ovaries and can then spread to the uterus. Its 

Other Possible Causes Of Abnormal Vaginal Bleeding

Sexually Transmitted Diseases

Chlamydia and gonorrhea can both lead to bleeding between periods. Pelvic inflammatory disease (PID) is a possible complication of both these diseases, which can lead to damaged reproductive organs and chronic pain. PID itself can also cause abnormal vaginal bleeding. Safe sex will do much to protect you from STDs, but it's always handy to be familiar with the symptoms various STDs can cause.

In women, chlamydia and gonorrhea have very similar symptoms: not normal vaginal discharge, pelvic pain, painful urination, and uncomfortable sexual intercourse. PID can cause fever, nausea and vomiting, diarrhea, irregular menstruation and infertility as well. 

Remember, chlamydia and gonorrhea in particular are often silent STDs in women. This means that you or your partner could have been infected during a previous relationship years ago, and still be clueless. In other words, STDs aren't the sole domain of the sexually promiscuous. Only testing will rule out STDs, and earlier treatment will help prevent complications. 

A Thyroid Disorder

Hypothyroidism means that your thyroid is underactive and does not produce sufficient quantities of certain hormones, while hyperthyroidism means your thyroid is overactive. Both are associated with abnormal vaginal bleeding. 

If you have an underactive thyroid, you may experience fatigue, weight gain, depression and dry skin among other symptoms. An overactive thyroid causes weight loss, a rapid heart beat, anxiety and irritability, and increased sweating. 

While symptoms tend to become more severe over time if thyroid disorders are left untreated, most women respond well to hormonal medications. 

Ectopic Pregnancy Or Miscarriage

An ectopic pregnancy is a pregnancy in which a fertilized egg implants outside the uterus. The fallopian tubes are the most common site for an ectopic pregnancy, and a pregnancy that develops in a fallopian tube is also called a tubal pregnancy. Tubal pregnancies cannot be carried to term, and can cause the relevant tube to rupture if it is not removed early on. Sharp pain and bleeding, nausea, light-headedness, fainting and shock can occur once the tube is about to rupture or has already ruptured. An ectopic pregnancy will still result in a positive pregnancy test.

A miscarriage is another obvious cause of abnormal vaginal bleeding. Women who are aware that they are pregnant when they start bleeding don't have to wonder about the cause of their bleeding, but miscarriage can still be a possible cause of bleeding in women who were not aware they were pregnant. Some women misinterpret an implantation bleeding as a period, and don't realize they are expecting. 

Hormonal Birth Control

Women who are using combined oral contraceptives ("the pill") or some other type of hormonal birth control can usually point the blame for any mid-cycle bleeding there. Mid-cycle bleeding is especially common in women who have recently started using hormonal contraceptive methods.

The withdrawal bleeding you experience after finishing a pill cycle can also be termed unusual vaginal bleeding, as this bleeding isn't actually a period — though it looks much like one. Women who frequently experience mid-cycle bleeding while using hormonal contraceptives, or whose bleeding persists even after two or three months of starting the pill, can ask their healthcare provider for advice. It is not, however, something you should worry about.

Other Causes Of Mid-Cycle Bleeding

We've listed a huge number of possible causes of mid-cycle bleeding or spotting here, and we're still not done — unusual vaginal bleeding simply has many possible causes. Others we didn't discuss include celiac disease, hormonal imbalances, Polycystic Ovary Syndrome (PCOS), low platelet counts, a side effect of the drug Tamoxifen, vaginitis, rough sexual intercourse, and the perimenopause. 

As you've seen, many causes of mid-cycle bleeding are benign and won't lead to serious harm even if you don't go to the doctor. Since some serious conditions — including cancer — can also make you bleed at times when you wouldn't normally expect it, all women who suffer from bouts of bleeding or spotting should pay their gynecologist or family doctor a visit.