Anovulation is the term for when your body is unable to reach the oestrogen threshold necessary to trigger ovulation so ovulation doesn't occur, meaning that conception is impossible that cycle.
You can have what appears to be a period without ovulating, but the bleeding is often different, heavier or lighter than your usual period and isn't technically a period at all. This bleeding might be what's known as oestrogen withdrawal bleeding, or could occur when the lining of the uterus builds to an unsustainable level and then begins to disintegrate.
It's more obvious that you're not ovulating when your periods stop altogether for a time, resulting on one, very long, cycle, which could last for several months. If you have previously had regular periods and go for six months without a period, or if you were irregular and go for twelve months without a period, then you are said to be experiencing amenorrhea.
Why does anovulation occur?
Anovulation can occur for many reasons which largely fall into three groups:
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Natural life phases
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Temporary influences
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Medical conditions
1. Natural life phases
The onset of menstruation - when girls first start their periods they usually take some time to settle into a regular, ovulatory pattern and anovulatory cycles are quite common.
Pregnancy - Obviously you don't ovulate when you're pregnant as a second pregnancy would jeopardise the first.
Breastfeeding - It's usual for women who are breastfeeding not to ovulate for a few months, which is a natural protection from pregnancy for a body that needs time to recover.
Menopause - As the menopause starts cycles often shorten before becoming gradually longer before stopping altogether, this usually happens to women as they reach their fifties.
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Anovulation can last for months at a time
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One of the ThinkBaby team went without a period for seven months when she travelled around South America on a gap year.
Another stopped her periods for over a year while she battled with anorexia.
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2. Temporary influences
Temporary influences can prevent your body from building up to the threshold level of oestrogen. Common factors include: illness, such as fever, travel, stress, low body fat and coming off the pill. It's common for professional athletes and women with eating disorders to experience anovulation as their low fat to weight ratio prevents them from reaching threshold oestrogen.
3. Medical conditions
Several medical conditions can disrupt or prevent ovulation, these include: Polycystic Ovarian Syndrome (or PCOS), thyroid disorders, Premature Ovarian Failure, Anorexia nervosa or conditions following surgical procedures such as Sheehan and Asherman's syndromes. If you think you may have one of these medical conditions then you should consult your doctor as soon as possible.
