Anovulatory Cycle · What Is It, Causes, Treatment, and More

An anovulatory cycle, also referred to as anovulation, refers to a menstrual cycle in which the release of an egg from the ovaries does not occur.  Chronic anovulation, or anovulation that persists for a year or longer, can be a common cause of infertility.  

In general, the menstrual cycle refers to the hormonal process where the body prepares for a potential pregnancy. The menstrual cycle is marked by monthly bleeding, commonly referred to as one’s “period” or menstruation. It also typically involves ovulation, or the release of an ovum (i.e., egg), midway through each cycle. Although individuals with an anovulatory cycle do not experience ovulation, they may still experience bleeding due to changes in hormone levels. This bleeding is usually referred to as withdrawal bleeding.  

Many different factors can lead to an anovulatory cycle; however, anovulation is most commonly related to hormone imbalances. Ovulation, or the release of an egg, is a complex process that involves many different hormones, including progesterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH). To trigger ovulation, hormone levels must reach a certain threshold for the release of an egg to occur. Any disruptions in this process can lead to anovulatory cycles.  

Disruption of ovulation hormones can occur when using certain hormonal birth control methods, like the pill, patch, injection, ring, or some hormonal intrauterine devices (IUD), as these birth control methods are designed to prevent ovulation. Being underweight or overweight, exercising excessively, or not consuming enough calories can also induce hormone imbalances that may cause an individual to experience anovulatory cycles. In addition, significant stress can affect hormone levels in the body and subsequently disrupt ovulation. Finally, polycystic ovary syndrome, or PCOS, is a common condition that causes anovulation by triggering the body to overproduce hormones, like testosterone and LH. The high levels of these hormones may result in anovulation.  

Irregular periods or lack of a period can be signs of anovulation. Menstrual bleeding that is lighter or heavier than usual may also suggest an anovulatory cycle. For those trying to conceive, infertility, or the inability to get pregnant, can also be a sign of anovulation. Regardless, most anovulatory cycles occur without any noticeable signs.  

Without ovulation, progesterone levels remain lower than they should be while estrogen levels rise, which results in unopposed estrogen activity. Normally, estrogen stimulates the growth of the endometrial lining. Without progesterone to stabilize it and trigger its shedding, the endometrial lining keeps growing, increasing the risk of irregular or heavy bleeding. Long-term unopposed estrogen significantly increases risk of endometrial hyperplasia and endometrial cancer, which is why treatment of anovulation is generally recommended, even if an individual isn’t trying to conceive. 

The first step in diagnosing anovulation is to determine if ovulation is occurring. This can be accomplished through a medical history, physical exam, and review of the individual’s menstrual schedule. Reviewing accompanying symptoms, such as breast tenderness, cervical mucus discharge, and body temperature while resting, can also be helpful in diagnosing an anovulatory cycle. That’s because normally there is a rise in body temperature around the time of ovulation due to the influence of higher progesterone levels. This increase happens about 1 day after ovulation and persists until the next period. 

Blood tests may also be conducted based on the medical advice of the healthcare provider. Blood tests can measure levels of progesterone, prolactin, thyroid hormone, testosterone, and other sex hormones like estrogen, FSH, and LH. Sometimes, ultrasound imaging may be recommended to look for any concerns in the ovaries or lining of the uterus. A referral to a gynecologist or fertility clinic may also be recommended in cases of chronic anovulation.  

The treatment for an anovulatory cycle is largely dependent on the cause, but it often begins with lifestyle changes. If the cause of anovulation is due to the individual’s weight, then returning to and maintaining a healthy body weight can help trigger ovulation. In addition, stress management, good nutrition, and moderate physical activity may encourage the body to correct hormone imbalances. In individuals with PCOS, combined oral contraceptives (COCs) or hormonal IUDs can help regulate bleeding and prevent endometrial overgrowth from unopposed estrogen activity. Alternatively, progesterone-only pills (i.e., “mini pill”) can be given certain days a month to mimic the natural cycle and protect the endometrial lining.  

If fertility is the goal, medications that increase hormone levels, like clomiphene citrate or letrozole, may be prescribed to help trigger the release of an egg. In cases where the induction of ovulation with medications has not been successful, in vitro fertilization (IVF) may be an alternative path to pregnancy. IVF is a procedure in which eggs are retrieved from the ovaries using medications, so ovulation need to occur spontaneously. The retrieved eggs are then fertilized with sperm and implanted in the uterus. IVF is typically reserved for those who have been experiencing anovulation for over a year. It is also helpful when there are age-related fertility concerns or when other infertility causes are present (e.g., tubal blockage, male factor infertility, etc.). 

Even in individuals who are not trying to conceive, treating chronic anovulation is recommended to prevent complications like endometrial hyperplasia and endometrial cancer.