Why Are My Periods So Irregular?


Dr. Steven Jay Fern

Most women, at some point in their life, experience “abnormal” vaginal bleeding, an episode of  bleeding that is clearly distinct from their usual and routine cycle.  In reality regular, cyclical vaginal bleeding known as “the period” is not a flawless process beginning at adolescence, and ending abruptly at menopause without ever missing a beat.   Although most cases of irregular vaginal bleeding are transient, or are from benign treatable conditions, the occurrence can cause a tremendous amount of fear and frustration for many women.

Unexpected or abnormal bleeding episodes may be sporadic, or they may be recurrent and disruptive to a women’s life.  A women can experience heavy bleeding at the time of the period, or bleeding can occur at frequent unexpected times.  In some cases several months may pass before any bleeding is noted. The amount of bleeding can range from light to heavy and at times profuse necessitating immediate medical therapy.

Causes of irregular bleeding can be divided for simplicity into those caused by hormonal irregularities and those due to pathologic findings in the reproductive tract.

Hormonal causes

Hormonal causes  of  abnormal vaginal bleeding are most often from untimely or absent ovulation – the process of releasing an egg from the ovary which should occur around the middle of a women’s menstrual cycle.
Normally, the hormonal changes which take place in  response to ovulation (in the absence of pregnancy occurring) acts as a signal that prepares the uterus for menstruation to occur in approximately 14 days, thus maintaining the regular monthly period.  Without this natural signal the uterus will bleed at an unexpected time which can be weeks to months later and often presents with either intermittent spotting or severe bleeding.   A skipped ovulation occurs in most women at some point in their life and simple causes may  be excessive exercise, changes in diet, stress, or approaching menopause and adolescence.   Recurrent absence of  ovulation may, however, signal certain gynecologic or endocrinologic disorders and deserves evaluation.

Other hormonal causes of bleeding may stem from occasional imbalances in the hormones estrogen and progesterone.   Normal levels of these hormones are required for a regular ordered menstrual cycle.  These imbalances can cause bleeding to occur at various times during the cycle.   Causes in some cases may be secondary to a women’s existing hormonal medication such as; birth control pills, Depo-Provera, and estrogen replacement therapy.  Other causes also include breast-feeding,   hormone producing ovarian cysts, or simply from occasional transient hormonal changes in a women’s body.

Pathologic Findings in the Reproductive Tract

Vaginal bleeding may be a response to abnormal changes in the uterine cavity or rarely even the cervix or vagina.  The most common pathologic causes include polyps and fibroids.   Endometrial polyps are benign localized overgrowths of the lining of the inside of the uterus, Fibroids are benign tumors which are made up of muscle cells and can grow to very large sizes.  Some fibroids like polyps grow into  the lining of the uterus and can severely disrupt a women’s menstrual cycle and induce bleeding irregularly and at times excessively.  Polyps unlike fibroids can also grow on the cervix and cause bleeding from here as well.

The least likely cause of abnormal vaginal bleeding is cancer of either the uterus or cervix, which can present with unexpected bleeding.    Although rare, this problem makes it especially important to evaluate women who are around the time of  menopause and postmenopause where the incidence increases.   It is important to realize, however, that the most common cause of bleeding in these women is physiologic estrogen deficiency; the natural process of declining estrogen levels in a women’s body.


Evaluation of abnormal vaginal bleeding begins with a careful history and physical exam. In addition in some women a pregnancy test is necessary as pregnancy itself is the most common cause of  “abnormal” vaginal bleeding in women <40 years old and should be ruled out first in a work up as treatment and further investigation depend on this.   Bleeding occurs in approximately one-third of all pregnancies in the first 12 weeks of gestation.  Most bleeding episodes of this nature are normal and pregnancies continue on in a healthy fashion, however investigation may be necessary to confirm a normal pregnancy as some abnormal pregnancies do present this way.

Most problems can be solved from the initial consultation.  It may also be necessary to obtain certain blood tests to help pin point a hormonal cause.

If suspicion by the health care practitioner exists for the possibility of uterine fibroids or polyps either from the history or from the physical exam, more information can be obtained from a sonogram.  The sonogram can also evaluate the ovaries for cysts.  At times direct visualization of the inside of the uterus, known as the endometrial cavity, may be necessary.  This can be accomplished by a technique called hysteroscopy, which is an outpatient procedure done in the hospital or office whereby a  camera is inserted up the cervix into the uterus. In some women over the age of 40 it may sometimes also be necessary to perform an endometrial biopsy to rule out the possibility of cancer.


The scope of treatment options is beyond the discussion in this article.  Treatment, however,  is only necessary if  bleeding is found to be excessive or recurrent.  Usually therapy is with hormones such as birth control pills or progesterone, or an adjustment in a patient’s current prescription, but occasionally if uterine fibroids, polyps or ovarian cysts are found, surgery may be necessary. Removal of fibroids or polyps along the lining of the uterus can be done by hysteroscopy, which allows the gynecologist to directly visualize and remove them. Most ovarian cysts implicated as a cause of irregular bleeding rarely need to be operated on, but if necessary most can be removed laparoscopically.  There are some patients in whom no definitive cause of the bleeding can be ascertained and hormonal treatment offers little or no relief.  These patients may respond to a procedure known as endometrial ablation, which destroys the ability of the uterine lining to continue to cause bleeding. Hysterectomy should remain the last resort reserved primarily for patients with larger fibroids or those patients who fail attempts at treatment with hysteroscopy or hormonal administration.

Unexpected or abnormal vaginal bleeding is a common problem that women face.  There are many different ways that irregularities in vaginal bleeding can present.  The various causes can most often be ascertained by your health care professional and treatments when necessary are usually simple and effective.  Patients should understand their bodies and what causes their bleeding, and should be actively involved in treatment decisions.  This approach will help reduce patient anxiety and bring about a more successful outcome.

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