INFERTILITY CAUSES- OVULATORY FACTORS
There are three essential parts to ovulation. Each one must be intact for normal fertility. The first step is growth and development of an egg. There are many thousands of eggs in a resting state within each ovary. One egg is selected to develop and be released in each monthly cycle.
The pituitary gland, at the base of the brain, produces FSH (follicle stimulating hormone). FSH circulates in the blood and acts on the selected egg to begin development. As the egg develops, fluid forms around it, and it becomes a small cyst within the ovary- now called a follicle. As that growth occurs FSH also stimulates cells that surround the egg to make estrogen (estrogen rises in the blood circulation as the follicle grows).
The rising estrogen acts on the uterine lining- the endometrium – to make it thickened and ready for the arriving fertilized egg. The length of the egg growth part of the ovulation cycle (the “follicular phase”) is usually 14 days but that can vary from 7-20 days and still be normal.
When egg growth is complete, the pituitary gland briefly produces a large amount of another hormone-LH (luteinizing hormone). This leads to the second step in ovulation- egg release. LH makes the ovary release the egg by rupture or breaking open the follicle- then the egg comes out to be picked up by the fallopian tube. The sperm travel up the fallopian tube, fertilize the egg within the tube and then the fertilized egg moves toward the uterus. Ovulation predictor kits test for the increase in LH (LH surge).
After the egg is released the follicle that contained it performs another function-it makes the hormone progesterone (produced by the same cells that made estrogen in the first part of the cycle). This marks the third part of ovulation. Progesterone increases for 5 or 6 days and changes the endometrial lining-further preparing it for the arriving fertilized egg. If pregnancy does not occur, the progesterone hormone level falls and a menstrual period begins. The length of the second half of the menstrual cycle (the “luteal phase”) should be about 14 days-it may be as short as 12 days or as long as 16 and still be regarded as normal.
The Things That Can Go Wrong With Ovulation
Anovulation (failure to ovulate)
If the hormone signal from the pituitary gland to the ovary by way of FSH does not occur, there will be no egg development and ovulation will not occur. In this circumstance regular monthly bleeding is absent. Women with months of no menstrual bleeding are clearly not ovulating and testing is not required to establish that diagnosis. If women menstruate infrequently (every few months) they may be ovulating now and then- usually not frequently enough to conceive a pregnancy in a reasonable time-frame. If you do not have regular periods, we will test you for a wide variety of endocrine problems which may cause failure to ovulate including: Polycystic Ovary Syndrome, elevation of the hormone prolactin, thyroid disease and adrenal disease. Effective treatment is available for all these causes of ovulation failure.
Luteal Phase Defect (LPD)
Another possible problem with ovulation is LPD. After the egg is released the follicle that contained it changes its function and makes the hormone progesterone- as above. If progesterone production is insufficient infertility may result and this is called Luteal Phase Defect. LPD is not common- it occurs in less than 5% of infertile women based on medical texts.
The luteal phase should be 14 days long (12 days minimum). There are 2 ways to diagnosis LPD: measure progesterone levels in the blood and determine the length of luteal phase. The length of the luteal phase-determined by the time from ovulation predictor kit change to the onset of menstrual bleeding- is a useful marker for LPD. If this time period is less than 12 days LPD may be present. As your testing and treatment progresses, let us know if the length of your luteal phase is less than 12 days. (Basal body temperature graphs are not as useful for determining the precise time of ovulation or luteal phase length).
The direct blood measurement of progesterone level in luteal phase is also useful to make the diagnosis. With regard to progesterone testing, it is important to understand the normal pattern of progesterone production in luteal phase. Progesterone rises just after ovulation, reaches a peak 5 to 8 days after ovulation and then falls until menstruation begins. Studies that define normal levels of progesterone in the luteal phase are all based on testing performed at the time of peak production. We therefore, test in this exact time period to diagnosis LPD.
A single blood test for progesterone can suggest luteal phase defect, however it is important to recognize that the hormone progesterone is released in a pulsatile manner. A single level of progesterone that is in the normal range is certainly reassuring, similar to the situation where single low progesterone suggests LPD, but there is no definitive test for LPD. If you are concerned that you have LPD, you should talk more to your doctor about this diagnosis.
Treatment of Ovulation Problems
If anovulation –or complete absence of ovulation -is diagnosed, tests are performed to evaluate the pituitary gland, adrenal glands, thyroid and ovaries. If a clear cause for ovulation failure is diagnosed it will be addressed. Some women fail to ovulate or have LPD for no apparent reason- all hormonal evaluations are normal. Treatment is highly successful for all forms of ovulation failure and LPD. As previously explained, FSH is vital for normal ovulation-both egg production and normal luteal phase (progesterone production).
The key to treatment of anovulation or LPD is increasing the level of FSH. This will result in proper egg development and progesterone production after ovulation. FSH can be increased indirectly by giving Clomiphene Citrate (Clomid, Serophene) or by giving FSH directly – Gonadotropins (Follistim, Repronex, Bravelle). We use both drugs-separate information sheets provide details on these therapies. In addition, treatment of LPD may be accomplished by giving progesterone (by vaginal suppository or by pill form) after ovulation. Progesterone treatment relies on the ovary to produce an egg and to release it.
Testing and Treatment to Meet Your Needs
We’re happy to tailor your therapy/testing to your situation. If you want to learn more about your luteal phase we will be pleased to offer testing and treatment options to individualize your care.