Anovulation occurs when a woman fails to ovulate, and an egg does not release from the ovaries. Ongoing (chronic) anovulation causes around 30% of female infertility. It is often caused by factors such as obesity, stress, low BMI, thyroid problems, and polycystic ovary syndrome (PCOS). Women using hormone contraceptives will often not ovulate.
Lifestyle changes, such as sticking to a balanced diet and maintaining a healthy BMI, are often the first step to overcoming anovulation. In certain situations, medical or fertility treatments, in conjunction with lifestyle changes, might be necessary.
How Does Ovulation Work?
The menstrual cycle has four stages. These four stages are caused by the rise and fall of the hormones progesterone and oestrogen which trigger the stages in your menstrual cycle. These hormones cause your reproductive organs (uterus, ovaries and fallopian tubes) to respond in certain ways.
Day 1 – 5 in your menstrual cycle is when you have your period (menstruate). This is when the lining of your uterus (womb) is shed if pregnancy has not occurred.
From days 6 – 14 (also known as the follicular phase) the level of oestrogen rises, which causes the endometrium to grow and thicken. Ovulation starts to happen when the hypothalamus (a gland in the brain) secretes gonadotropin-releasing hormone (GnRH), which then causes the pituitary gland (another gland in the brain) to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH causes follicles to grow in your ovaries. Between days 10 to 14, one of these follicles will form a fully mature egg (ovum). Luteinizing hormone (LH) causes your ovary to release its egg. The release of an egg is known as ovulation.
From days 15 – 28, an egg is released from your ovary and travels through your fallopian tubes and into your uterus. Progesterone levels start to rise to help prepare your uterine lining for pregnancy. If the egg becomes fertilised by sperm (conception) and attaches itself to your uterine wall (implantation), you become pregnant. If conception does not occur, hormone levels drop and the thick lining of your uterus is shed (your period).
How Is Anovulation Diagnosed?
The absence of regular menstruation is the primary indicator for diagnosing anovulation. However, further tests may be required to assess reproductive health thoroughly. These tests include evaluating female hormone levels, specifically blood progesterone levels, and conducting a pelvic ultrasound scan to observe ovarian activity and follicle production. Additionally, testing blood thyroid and prolactin levels and performing an ultrasound examination of the pelvic organs may be necessary. In some cases, additional tests such as assessing the lining of the uterus (endometrium) might be recommended for a comprehensive evaluation.
What Are The Causes Of Anovulation?
There are several health problems and risk factors associated with a woman’s inability to ovulate. These include:
- Obesity - A high BMI can cause a chemical imbalance to occur when there is an excess of testosterone.
- Stress - Excessive stress or anxiety can cause certain female hormones to become imbalanced.
- Low body weight and/or excessive exercise - A low BMI or regular intense physical exercise can affect a woman’s pituitary gland. This may cause the pituitary gland to not produce enough follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
- Abnormal thyroid/prolactin levels – Imbalances in either one of these can interfere with ovulation.
- Polycystic ovary syndrome (PCOS) - polycystic ovarian syndrome (PCOS) is one of the most common reasons for irregular menstrual cycles and anovulation. PCOS is caused by a hormone irregularity and occurs in about 10% of women. It is characterised by elevated levels of testosterone and causes menstrual abnormalities such as long cycles and a lack of ovulation. Women with PCOS often have more follicles in their ovaries than other people. Other symptoms may include acne and hirsutism (excessive facial hair growth).
- Certain medications – some medications are thought to interfere with a woman’s ability to ovulate. These include certain herbal supplements, NSAIDs (non-steroidal anti-inflammatory medication), epilepsy or seizure medications and cancer treatments.
- First and last periods - anovulation and abnormal or irregular periods are common when a girl first starts menstruating. It also can occur during perimenopause, when a woman in her 40s approaches menopause. Anovulation is both these cases is caused by hormonal imbalances.
- Hormonal Contraception – birth control pills, patches or IUDs containing oestrogen and/or progesterone often prevent ovulation.
What Are The Symptoms Of Anovulation?
Women with very irregular periods, or who do not see the usual signs of ovulation, may not be ovulating. If a woman is ovulating, she will notice certain changes during each cycle. Changes that normally occur in the middle of the menstrual cycle (around days 10-16) include increased amounts of cervical mucus and changes in body temperature. A change in hormones around ovulation causes your body temperature to increase by up to 0.3°C for 3 days while you are ovulating.
If you suspect that you are not ovulating (and you are not using contraceptives), you can purchase an over-the-counter ovulation predictor kit. These kits measure hormone levels in your urine to determine when you are ovulating. If your symptoms of anovulation continue, you should consult your healthcare provider.
How Is Anovulation Treated?
Anovulation can often be remedied by adopting healthier lifestyle choices, although in some cases medical treatment might be necessary. Treating anovulation usually requires:
- Lifestyle changes – the first step to overcoming anovulation should include maintaining a healthy BMI and following a nutritious, balanced diet. Nutritional counselling may be helpful for obese or underweight women.
- Changing exercise routine – if excessive exercise is the cause of your anovulation, you should moderate your exercise routine.
- Reducing stress – women suffering from stress and anxiety may consider counselling or stress management.
- Healthy eating - many fertility diets are advertised but the best diet is one that can be maintained over the long term.
- Social support - social support can be very helpful in supporting women who are trying to overcome anovulation. This may include talking to others, sharing recipes, going on walks together, or engaging in other similar group activities.
- Medical intervention – medical intervention should be used in conjunction with lifestyle modifications. Medications which stimulate ovulation may be prescribed. In-vitro fertilisation (IVF) or intrauterine insemination (IUI) may be recommended if ongoing infertility remains a problem.
Anovulation, the failure to ovulate, can significantly contribute to female infertility, accounting for approximately 30% of cases. Various factors, such as obesity, stress, low body mass index (BMI), thyroid issues, and polycystic ovary syndrome (PCOS), can lead to chronic anovulation. Women using hormone contraceptives often experience suppressed ovulation. Overcoming anovulation typically involves implementing lifestyle changes, including maintaining a healthy BMI and following a balanced diet. In some cases, medical interventions and fertility treatments may be necessary, alongside lifestyle modifications.