Once you understand how the menstrual cycle works, you can see how ovulation can fail or become unreliable. The following ovulation disorders can therefore occur:
Keeping in mind this basic explanation of how the menstrual cycle and ovulation works, it is now possible to understand how ovulation can fail or become unreliable. The following ovulation disorders can therefore occur:
- The higher centres of the brain do not send GnRH messenger to the pituitary gland. This is a common form of ovulation failure and may be particularly precipitated by such things as stress, diet, or possibly excessive exercise.
- The pituitary gland does not send messenger hormone FSH to the ovary to tell it to grow eggs. This often occurs in association with the higher brain centres failing to send down GnRH hormone, which releases FSH. However there are different forms of pituitary failure e.g. tumours, radiation damage, damage due to excessive blood loss or trauma and absence of the pituitary gland from birth.
- The pituitary gland sends mixed messages to the ovary with the wrong amounts of FSH and LH acting as conflicting messengers. The ovary is therefore unable to grow a mature egg in a logical and organised fashion. This form of ovulation disorder is commonly called polycystic ovary disease and is very common.
The ovary is absent or has no eggs. Some patients are born without ovaries. When the ovary runs out of eggs menopause occurs. This can sometimes occur in very young patients. If the patients are younger than 35 years they are described as having premature menopause. Sometimes the ovaries will have a small number of eggs left but be very resistant to the influence of FSH telling the eggs to grow. This condition is very difficult to pick from premature menopause and is called resistant ovary syndrome.
Other influences that can upset egg production include:
- Diseases of other glands e.g. the thyroid gland, adrenal gland, or diabetes or sugar intolerance.
- A special sort of pituitary tumour called a prolactinoma. Prolactin is the hormone, which produces breast milk. Prolactinomas grow in the pituitary gland and the hormone they produce reduces the production of FSH and therefore prevents ovulation.
- Exercise. Excessive levels of exercise e.g. marathon training or excessive gym work increase the level of chemicals called endorphins in the spine and brain. These have the effect of dampening FSH output by the pituitary gland. The ovary therefore receives significantly reduced messages telling it to grow and release an egg.
- Drugs and medicines. A wide range of these can inhibit or change ovulation. If you are on a medication it is best to consult your doctor and ask if this medication could specifically affect ovulation.
- Ovarian conditions such as cysts and endometriosis can sometimes interfere with the ovaries response to the messages it receives from the brain and the pituitary gland thereby preventing orderly egg growth and ovulation.
Find out more about treatments for ovulation disorders.