An irregular period, or oligomenorrhea, can be caused by a variety of factors. If you have been experiencing irregular periods, your gynecologist will determine the cause. The guide below discusses common causes of irregular periods so you can discuss potential sources of issues with your doctor.

What It Is

In a regular menstrual cycle, the length of time between each period and the amount of blood shed, are similar from month to month. The typical cycle is approximately 28 days and may vary a few days each time, ranging between 24 and 35 days.

An irregular cycle is defined as one that lasts more than 35 days or varies in length from month to month. It may also include abnormal uterine bleeding such as spotting between periods, unusually heavy bleeding during the period, or bleeding that lasts longer than usual. 

Common CausesHormonesgynecologist

Hormones such as estrogen and progesterone are responsible for regulating the cycle, so when levels change or are unusual, the cycle will not be regular. Hormone levels naturally change during puberty, pregnancy, childbirth, breastfeeding, and menopause. 

They may also change when a woman is starting, switching, or ending a hormone-based birth control method such as the contraceptive pill or an IUD. Your gynecologist can tell you what to expect with your birth control change. Stress hormones, such as cortisol, may trigger the body into fight-or-flight mode and delay ovulation. This can result in late or completely missed periods. 

Health Conditions

Polycystic ovary syndrome, or PCOS, occurs when cysts develop in the ovaries. This can cause unusually high levels of male hormones such as androgen and testosterone, which disrupt the cycle. 

Endometriosis occurs when the interior lining of the uterus, or endometrial cells, grows on the outside of the uterus. Menstrual blood can get caught in this tissue, which causes irregular periods often accompanied by severe pain. 

Eating disorders such as bulimia and anorexia do not supply the body with the nutrients it needs to produce enough hormones, so they may cause irregular or missed periods. Irregular menstruation can also accompany uncontrolled diabetes, hyperprolactinemia, thyroid disorders, uterine cancer, and pelvic inflammatory disease (PID).

When to See a Gynecologist

If you know your irregular period is not the result of birth control, stress, or life cycle changes, you may want to see your doctor. You should see them if your periods are extremely painful, if your cycle is more frequent than 21 days, if you haven’t had a period for 90 days, or if the bleeding lasts for more than a week. 


If you’re experiencing irregular menstrual cycles or unusually painful cramps, visit the doctors at Greece OB-GYN, LLP. These professionals offer women of all ages in Rochester, NY, extensive services, including adjusting birth control methods to ensure menstrual cycles remain consistent. Learn more about their services on their website and call (585) 225-6680 to schedule an appointment. They offer evening hours to better accommodate all patients’ schedules. 



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