Human biology

Changes in hormone levels can create poor oocyte quality. Controlling blood levels are also determining factors used to time oocyte retrieval and increase the number of oocytes that are retrieved (2005). The three hormones that can be tested so the best time for oocyte retrieval are LH (Luteinizing Hormone), oestradiol and progesterone.
An increase of LH is an important variable as it is an indicator that ovulation has begun and that the release of an oocyte has already begun. Many times if the LH levels are high, the possibility of retrieving mature eggs may be difficult, which is why most LH surges will delay the process of IVF.
Oestradiol stimulates the lining of the uterus, making it ready for the arrival of the embryo (2005). The longer the oestradiol level rises the more mature the eggs will be. The problem with measuring the oestradiol levels is that they vary from person to person. This variance can make it difficult to measure whether it is appropriate to have a high or increased oestradiol levels for four days as opposed to eleven days. Also, one level may be considered high for one person, but low for another.
Progesterone developed when the presence of LH increases and when oestradiol has readied the lining of the uterus for the embryo. This means that the presence of progesterone is acceptable during the process. However, levels that are considered too high for a particular patient are an indication that the quality of the eggs are poor.
‘The woman’s reproductive system is regulated by the hypothalamic-pituitary ovarian axis'(1998). "Neurons that secrete GnRH in the preoptic and arcuate nucleus areas and stimulate the production of follicle-stimulating and LH, which can in turn create oestradiol and progesterone'(1998). The presence of follicle is an indication that eggs are being produced and possibly mature. The more follicles that are present, the higher the oestradiol levels. The advantage of stimulating follicular development increases the likelihood of pregnancy as the uterus is ready and eggs are more likely to be mature and of good quality. Multiple oocytes are likely to be also.
Based on the figures present, it is clear that during normal cycles, the levels of LH, oestradiol and progesterone are affected. These hormonal levels are particularly affected by the presence of hormones. Hormonal levels are decreased with the use of certain steroids. Hormonal levels are much higher with treatments. Any hormone that stimulates ovulation is likely to increase the risk of multiple births. This is the case because ovulation inducement can create a "polyfollicular response," which increases the risk for multiple births as more than one egg is released (2004). IVF is known among the medical community to decrease the risk of unwanted multiple births. IVF is works effectively because the doctor and patient have a great amount of control over the process. IVF allows the physician to actually control the number of embryos that he/she implants. The fact that the process is so controlled increases the success rate of pregnancy even though only one embryo is implanted.
REFERENCES
Gemzell, Carl, 2004, Gonadotrophins and Steroid Hormones, viewed 06/13/2004, www.tylermedicalclinic.com
Gleider, Norbert, August 1 2004, Limiting Embryo