Anovulation

What is anovulation?

Anovulation means your ovary doesn't release an egg during your menstrual cycle, so ovulation doesn't happen. It's usually caused by a hormone imbalance, and is one of the most common causes of infertility.

What are the symptoms of anovulation?

You might not immediately notice anovulation, since you can still have some bleeding even when you haven't ovulated. Signs to look out for include:

• irregular periods, where the time between periods keeps changing
• very heavy or very light periods, or periods lasting longer than seven days
• missing one or more periods when you're not pregnant
• not noticing the clear, slippery, egg-white-like vaginal discharge that usually appears around ovulation
• an irregular basal body temperature (your temperature at rest, which normally rises slightly after ovulation)

Having a period doesn't necessarily mean you've ovulated. You can still bleed without ovulating – this is called abnormal uterine bleeding, and it's common, affecting around 30% of women at some point.

What causes anovulation and who is at risk?

Anovulation usually happens because of an imbalance in one or more of the hormones involved in ovulation, including those made by your brain's hypothalamus and pituitary gland. Common causes and risk factors include:

• polyendocrine metabolic ovarian syndrome (PMOS), previously known as polycystic ovary syndrome (PCOS), is the most common cause, which involves higher levels of male hormones (androgens) and affects around 1 in 10 women of childbearing age
• being significantly overweight or obese
• having a very low body weight, or doing intense, prolonged exercise
• high levels of the hormone prolactin
• an underactive thyroid
• high levels of stress.

You're also more likely to have anovulatory cycles just after your periods start, and again in the years leading up to the menopause (perimenopause), when hormone levels naturally fluctuate more.

Are there different types of anovulation?

Doctors often group anovulation by its underlying cause:

• Anovulation linked to polyendocrine metabolic ovarian syndrome (PMOS), the most common group
• Anovulation linked to problems with the hypothalamus or pituitary gland in the brain, often from low body weight, intense exercise or stress
• Anovulation linked to primary ovarian insufficiency, where the ovaries stop working as expected before the age of 40
• Anovulation linked to high prolactin levels (hyperprolactinaemia).

How is anovulation diagnosed?

The main sign that leads to a diagnosis of anovulation is having irregular periods. Your doctor will ask about your cycle and symptoms and may examine you. Tests that can help find the cause include:

• blood tests to check hormone levels, including progesterone, thyroid hormones and prolactin
• an ultrasound scan of your pelvic organs, to look at your ovaries and womb lining
• occasionally, a sample of tissue from your womb lining (an endometrial biopsy).

How is anovulation treated?

Treatment for anovulation focuses on correcting the hormone imbalance behind it, where possible, and depends on whether you're trying to get pregnant.

Non-surgical treatment

• Managing stress: Using techniques such as meditation, yoga or deep breathing
• Reaching a healthy weight for you: Whether that means losing or gaining weight – a doctor or dietitian can help you do this safely
• Reducing the amount or intensity of exercise: If this is thought to be contributing
• Medication to treat an underlying condition: Such as thyroid hormone replacement for an underactive thyroid
• Fertility medicines: Such as clomiphene citrate, which is often tried first and helps around 80% of women with anovulation to ovulate, or letrozole, which some doctors recommend instead
• Hormone injections: Such as human chorionic gonadotropin (hCG) or follicle-stimulating hormone (FSH), if other treatments haven't worked.

Surgical treatment

Surgery is not usually the first option for anovulation, but may be considered in specific circumstances:

• Laparoscopic ovarian drilling: This is a keyhole procedure sometimes used for PMOS-related anovulation if medication hasn't worked
• Surgery to remove a pituitary tumour (prolactinoma): If there is a large tumour causing high prolactin levels.

If fertility medicines and lifestyle changes don't lead to pregnancy, your doctor may discuss options such as intrauterine insemination (IUI) or in vitro fertilisation (IVF).

When should I see a doctor?

Contact a healthcare provider if:

• you have vaginal bleeding at unpredictable, random intervals
• your bleeding is very heavy, very light, or lasts longer than a week
• you have pelvic or abdominal pain
• you haven't conceived after six months of trying (if you're over 35) or one year (if you're under 35), despite having regular, unprotected sex.