ConditionWomen's & pregnancy health
Chronic Anovulation
Chronic anovulation means the ovaries release an egg rarely or not at all over months or years. It shows up as irregular, infrequent or absent periods, and is one of the most common causes of female infertility. Polycystic ovary syndrome (PCOS) causes most cases; others include thyroid disease, high prolactin, low body weight or intense exercise, and early loss of ovarian function. Without ovulation, the uterine lining is exposed to estrogen alone, so protecting it is part of treatment.
Also called: Anovulation, absent ovulation, ovulatory dysfunction, oligo-ovulation (infrequent ovulation)
At a glance
- What it is
- Long-term failure to ovulate regularly.
- Signs
- Periods more than 35 days apart, fewer than 8 a year, absent, or unpredictable heavy bleeding.
- Main causes
- PCOS, hypothalamic causes (low weight, exercise, stress), thyroid disease, high prolactin, premature ovarian insufficiency.
- Risks
- Infertility, and thickening of the uterine lining (endometrial hyperplasia) over time.
- Treatment
- Treat the cause; hormonal therapy to protect the uterus; ovulation induction (letrozole) for pregnancy.
When to get help
Call 911 or go to the ER
- Very heavy bleeding soaking a pad or tampon every hour for 2 or more hours, or with dizziness or fainting
See a doctor within a day or two
- A positive pregnancy test with pelvic pain or bleeding
- Heavy, prolonged bleeding after months without a period
Book a routine appointment
- Periods more than 35 days apart, fewer than 8 a year, or no period for 3 months
- Trying to conceive for 12 months (or 6 months if 35 or older) with irregular periods
- Irregular periods with excess facial or body hair, acne or weight gain
- Milky nipple discharge, headaches or vision changes with missed periods
- Hot flashes and missed periods before age 40
What anovulation means
In a typical menstrual cycle, rising hormones from the brain (FSH and LH) cause one follicle in the ovary to mature and release an egg around mid-cycle. Afterward, the ovary makes progesterone, which stabilizes the uterine lining. If pregnancy does not happen, progesterone falls and a period follows about 14 days later.
In anovulation, no egg is released, so no progesterone is made. Bleeding then becomes irregular: periods may stop, come infrequently, or arrive unpredictably and heavily when the estrogen-stimulated lining becomes unstable.
Occasional anovulatory cycles are normal, especially in the first years after periods start and in the years before menopause. Chronic anovulation means a long-term pattern that needs evaluation. See anovulation for the general definition.
Signs you may not be ovulating
- periods more than 35 days apart, or fewer than 8 periods a year
- no periods at all (amenorrhea)
- unpredictable bleeding, sometimes very heavy or prolonged
- no premenstrual symptoms such as breast tenderness
- ovulation tests or basal body temperature charts showing no ovulation pattern
- difficulty getting pregnant
Causes
| Cause | Mechanism | Clues |
|---|---|---|
| Polycystic ovary syndrome | Hormone imbalance with high androgens and insulin resistance | Irregular periods, acne, excess hair, weight gain, many follicles on ultrasound |
| Hypothalamic amenorrhea | The brain reduces signals to the ovaries | Low weight, intense exercise, stress, under-eating |
| Hyperprolactinemia | High prolactin suppresses ovulation | Milky nipple discharge, headaches, certain medicines |
| Thyroid disease | Both underactive and overactive thyroid disrupt cycles | Fatigue, weight change, heat or cold intolerance |
| Premature ovarian insufficiency | Ovaries stop working before 40 | Hot flashes, night sweats, vaginal dryness |
| Obesity | Excess estrogen and insulin disrupt signaling | Often overlaps with PCOS |
| Other | Cushing syndrome, congenital adrenal hyperplasia, pituitary tumors | Specific symptoms |
PCOS accounts for most cases of chronic anovulation in women of reproductive age.
Health effects
- Infertility: ovulatory problems cause about a quarter of female infertility.
- Endometrial hyperplasia and cancer: without progesterone, the uterine lining can thicken over years, raising the risk of endometrial cancer. Having fewer than about 4 periods a year is a reason to take protective treatment.
- Heavy, irregular bleeding and anemia.
- Bone loss in hypothalamic amenorrhea and premature ovarian insufficiency, due to low estrogen.
- Metabolic risks in PCOS: type 2 diabetes, high cholesterol and sleep apnea.
Diagnosis
- Menstrual history and a pregnancy test
- Blood tests: FSH, LH, estradiol, prolactin, thyroid function (TSH), testosterone and sometimes AMH; a progesterone level about a week before an expected period confirms whether ovulation occurred
- Pelvic ultrasound to look at the ovaries and uterine lining
- Glucose and lipid tests in PCOS
- Endometrial biopsy if there is prolonged abnormal bleeding, especially over age 35 or with risk factors
Treatment
Treating the cause
- PCOS: lifestyle changes; weight loss of 5 to 10 percent can restore ovulation in some people; metformin for insulin resistance.
- Hypothalamic amenorrhea: restoring energy balance by eating more, reducing training, and managing stress.
- High prolactin: stopping causative medicines; dopamine agonists such as cabergoline; treatment of a pituitary tumor.
- Thyroid disease: thyroid hormone replacement or treatment of an overactive thyroid.
Protecting the uterus (not trying to conceive)
- combined hormonal contraceptives (pill, patch or ring)
- cyclic progestin tablets to trigger regular withdrawal bleeds
- a levonorgestrel IUD, which protects the lining and reduces bleeding
Inducing ovulation (trying to conceive)
- Letrozole: now the first-line ovulation induction medicine for PCOS, with higher live birth rates than clomiphene
- Clomiphene citrate: an alternative
- Gonadotropin injections: for those who do not respond, or for hypothalamic causes
- Laparoscopic ovarian drilling in selected cases
- IVF when other methods fail or other fertility factors exist
Monitoring with ultrasound is used to reduce the risk of multiple pregnancy.
Frequently asked questions
What are the signs of anovulation?
The main signs are periods that are far apart, very irregular or absent, sometimes with unpredictable heavy bleeding. Ovulation tests may never turn positive. Difficulty getting pregnant is often how anovulation is discovered.
What causes chronic anovulation?
Polycystic ovary syndrome is the most common cause. Others include low body weight or intense exercise affecting the brain's signals, high prolactin, thyroid disease, obesity and premature ovarian insufficiency. Blood tests usually identify the cause.
Can you get pregnant if you don't ovulate?
Not without ovulation, but treatment works well. Medicines such as letrozole or clomiphene trigger ovulation in most women with PCOS, and treating causes such as thyroid problems or high prolactin often restores natural ovulation.
Is anovulation dangerous?
It is not immediately dangerous, but long-term anovulation can lead to thickening of the uterine lining and a higher risk of endometrial cancer. It can also cause heavy bleeding and anemia. Regular hormonal treatment protects the uterus.
How is chronic anovulation treated?
Treatment depends on the cause and whether you want to conceive. Options include lifestyle changes, treating thyroid or prolactin problems, hormonal contraceptives or progestins to protect the uterus, and letrozole or other medicines to trigger ovulation for pregnancy.
Sources
This guide was written from current patient and clinical guidance, including:
- American College of Obstetricians and Gynecologists: Polycystic Ovary Syndrome (Practice Bulletin)
- American Society for Reproductive Medicine: Ovulation Induction Patient Fact Sheet
- International Evidence-based Guideline for the Assessment and Management of PCOS (2023)
- Endocrine Society: Functional Hypothalamic Amenorrhea Guideline
- MedlinePlus: Anovulatory bleeding