What is Anovulation? Signs and Causes

What is Anovulation?

When a person experiences anovulation it means that their ovaries have not released a mature egg which can have a detrimental impact on fertility.

Ovulation is a normal stage within the menstrual cycle and happens when a mature egg is released from one of the ovaries in preparation for fertilisation. Usually, ovulation occurs mid-cycle and is a result of several hormonal fluctuations.

For example, during a normal cycle, your brain releases gonadotropin-releasing hormone which causes follicle-stimulating hormone (FSH) levels to rise, and triggers the ovarian follicles to develop an egg. A rise in luteinising hormone (LH) signals one of the ovaries to release a mature egg. Once this has occurred, oestrogen, FSH, and LH levels fall, while progesterone levels start to increase, in preparation for pregnancy.

So, if an egg isn’t released, ovulation hasn’t occurred and you won’t be able to get pregnant.

How common is anovulation?

Sporadic anovulation is relatively common, with the chances of not ovulating ranging from 1% to 14.5% per menstrual cycle^[1]. In the most severe cases, a quarter of female infertility cases are thought to be caused by disorders affecting ovulation^[2].

How long does anovulation last?

Anovulation can be temporary or long-term (chronic). For temporary anovulation, medication and lifestyle changes may help to treat the condition, depending on the cause.

What happens to my period if I don’t ovulate?

If you are not ovulating, your periods may stop or become irregular. Periods occur because an egg isn’t fertilised and implanted in your womb, so it’s the womb lining shedding, ready to repeat the process in your next cycle.

However, some people do experience a ‘bleed’ similar to a period when they are not ovulating. One of the most common causes of bleeding during an anovulatory cycle is abnormal uterine bleeding^[3]. During an anovulatory cycle, the process remains the same, so the lining of the uterus is still shed but no egg is released. Because of this unpredictability, it can be frustrating if you’re trying to conceive because it can make it more difficult to plan intercourse and track your fertility.

How common is anovulation in the UK?

Anovulation is relatively common in the UK with 25% of infertility cases being caused by ovulatory disorders^[4]. Polycystic ovary syndrome (PCOS) is one of the most common reasons for an absence of ovulation^[5]. The prevalence of PCOS in the UK is approximately 1 in 10 women^[6].

Signs of Anovulation

The signs of anovulation can vary between women. Some of the common signs of anovulation include:

• Amenorrhoea

  This is when a woman doesn’t have a period. Some women who do not ovulate also don’t experience their period.

• Irregular periods

  Women with anovulation can experience irregular periods, spotting, or longer menstrual cycles (over 35 days).

• Silent ovulation

  Some women who experience an anovulatory cycle can also get regular periods. This is known as silent ovulation and is a sign that ovulation may be occurring during some menstrual cycles.

When ovulation occurs, it’s common for women to experience some of the common ovulation-associated symptoms, such as:

• sore or tender breasts

• increased body temperature

• changes in cervical mucus e.g. egg white consistency and colour

If ovulation doesn’t occur, you may not experience these symptoms which can be a sign of anovulation.

Can a woman with anovulation get pregnant?

If you experience an anovulatory cycle, it isn’t possible to get pregnant because an egg hasn’t been released from your ovaries. Many women with anovulation can get pregnant, but it can be more difficult and may require some treatment or lifestyle changes.

What Causes Anovulation?

There are several causes of anovulation but they are all fundamentally related to hormonal imbalances.

Hormone changes and imbalances happen for many reasons and do not necessarily need to be caused by an underlying medical condition. Instead, they may be induced by lifestyle factors such as diet or overexercising.

Here are some of the common reasons that may stop ovulation from happening:

• Polycystic ovary syndrome

  PCOS is a relatively common hormonal imbalance that causes an overproduction of male hormones, like testosterone, leading to the development of acne and hirsutism (excess hair growth). However, it also affects ovarian function and can cause anovulation.

• Menopause

  Anovulation is common during perimenopause, the transition towards menopause where you may experience symptoms but your periods haven’t stopped^[7]. As you progress through perimenopause, you may notice your menstrual cycles become longer or shorter. Both are associated with anovulation^[8].

• Thyroid issues

  Disturbed thyroid hormone levels can affect how follicles develop in the ovaries^[9].

• Obesity

  A high body mass index (BMI) or excess weight can cause an overproduction of androgens, like testosterone, and can impact ovulation and the menstrual cycle^[10].

• Being underweight or excessive exercise

  As much as being overweight can impact your fertility and ovulation status, so too can being underweight or exercising excessively. Both can delay ovulation by impacting the areas of the brain that are responsible for hormone production.

• Stress

  Chronic stress can cause imbalances in many of the hormones involved in the menstrual cycle and ovulation, such as gonadotropin-releasing hormone (GnRH), LH, and FSH^[11].

Treating Anovulation

The treatment for anovulation will depend on what’s causing your ovaries to not release an egg as well as your personal circumstances. Some of the anovulation treatment options include:

• Lifestyle changes

  Making small changes to your lifestyle can sometimes be enough to kickstart your ovaries into ovulating. Things that can help include maintaining a healthy weight, managing stress, getting the right amount of exercise, and following a healthy, balanced diet.

• Medication

  Some women may be prescribed medications to help induce ovulation or improve fertility, such as clomifene, tamoxifen, or gonadotropins^[12]. Your doctor can discuss what is available and most suitable for you.

• Surgical intervention

  In extreme cases, interventions such as in vitro fertilisation (IVF) may be required to achieve pregnancy.