Anovulation (Not Ovulating)

What anovulation means

In a typical cycle, rising hormones from the brain (FSH and LH) cause a follicle in the ovary to mature and release an egg around mid-cycle. The empty follicle then makes progesterone, which stabilizes the uterine lining and leads to a predictable period about 14 days later if pregnancy does not occur.

Without ovulation, no progesterone is made. The lining builds up under estrogen alone and sheds irregularly. That is why anovulation causes:

• no periods (amenorrhea) or infrequent periods (oligomenorrhea)
• unpredictable bleeding, sometimes heavy or prolonged
• infertility, since no egg is available

Infrequent ovulation is called oligo-ovulation.

Can you have a period without ovulating?

Yes. Bleeding can occur without ovulation when the estrogen-stimulated lining becomes unstable and breaks down. This anovulatory bleeding is usually irregular in timing and amount. A regular cycle of 24 to 38 days with premenstrual symptoms and cramps suggests ovulation is happening; irregular cycles suggest it may not be.

Causes

Polycystic ovary syndrome (PCOS)

PCOS is the most common cause of anovulation, accounting for most cases of anovulatory infertility. It involves high androgen levels and insulin resistance, causing irregular periods, acne, excess hair growth and often weight gain.

Hypothalamic causes

The hypothalamus in the brain reduces its signals to the ovaries when the body is under strain:

• low body weight or eating disorders
• intense exercise, especially with low energy intake
• significant emotional stress
• severe illness

This is functional hypothalamic amenorrhea, and it also lowers estrogen, putting bones at risk.

Hormonal disorders

• Hyperprolactinemia: high prolactin from a pituitary tumor or medicines, sometimes with milky nipple discharge.
• Thyroid disease: both hypothyroidism and hyperthyroidism.
• Cushing syndrome and congenital adrenal hyperplasia.

Ovarian causes

• Premature ovarian insufficiency: the ovaries stop working normally before age 40, with hot flashes and missed periods.
• Perimenopause: anovulatory cycles become common in the years before menopause.

Life stages

• the first 1 to 2 years after periods begin
• breastfeeding
• after stopping hormonal contraception, for a few months

Obesity and medicines

Obesity can disrupt ovulation even without PCOS. Some antipsychotics and other medicines that raise prolactin can stop ovulation.

Diagnosis

1. Cycle history: a menstrual diary or app record over several months.
2. Mid-luteal progesterone: a blood test about 7 days before the expected period (day 21 of a 28-day cycle). A raised level confirms ovulation.
3. Ovulation predictor kits detect the LH surge in urine; basal body temperature charting shows a rise after ovulation.
4. Blood tests: pregnancy test, TSH, prolactin, FSH and LH, estradiol, testosterone, and sometimes AMH, glucose and lipids.
5. Pelvic ultrasound: looks at the ovaries (PCOS features) and uterine lining.

Treatment

Treat the underlying cause

• weight loss of 5 to 10 percent in people with obesity or PCOS often restores ovulation
• restoring nutrition and reducing excessive exercise in hypothalamic amenorrhea
• thyroid medicine for thyroid disease
• dopamine agonists (cabergoline, bromocriptine) for high prolactin

If you want to become pregnant

• Letrozole: an oral medicine taken for 5 days early in the cycle. It is the first-line choice for PCOS-related anovulation, with higher live birth rates than clomiphene in trials.
• Clomiphene citrate: an alternative oral ovulation inducer.
• Metformin: may help in PCOS, especially with insulin resistance, alone or with other treatments.
• Gonadotropin injections: used when tablets do not work, with ultrasound monitoring to limit the risk of multiple pregnancy and ovarian hyperstimulation.
• Pulsatile GnRH for hypothalamic causes.
• IVF if other approaches fail or there are additional fertility factors.

If you do not want to become pregnant now

Long-term anovulation without progesterone can cause the uterine lining to overgrow (endometrial hyperplasia), raising the risk of endometrial cancer. Combined hormonal contraception, cyclical progestins or a hormonal IUD protect the lining and regulate bleeding.

Outlook

Most people with anovulation can ovulate with treatment, and many conceive. Treating chronic anovulation also protects against endometrial overgrowth and, in hypothalamic causes, bone loss.

Frequently asked questions

What are the signs of anovulation?

Signs include irregular or absent periods, cycles shorter than 21 or longer than 35 days, unpredictable heavy or light bleeding, no premenstrual symptoms, no rise in basal body temperature, negative ovulation tests, and difficulty getting pregnant.

What causes anovulation?

PCOS is the most common cause. Others include low body weight, intense exercise and stress affecting the brain's signals, thyroid problems, high prolactin, premature ovarian insufficiency, perimenopause and breastfeeding.

Can you get pregnant with anovulation?

Not during a cycle without ovulation, but many people ovulate occasionally and can conceive. Treatment such as weight loss in PCOS or medicines like letrozole or clomiphene restores ovulation in most cases, and many go on to conceive.

How is anovulation treated?

Treatment depends on the cause and your goals. Options include lifestyle changes, treating thyroid or prolactin problems, ovulation-inducing medicines such as letrozole for pregnancy, and hormonal contraception or progestins to regulate bleeding and protect the uterine lining.