How hormones work
| Ovarian stimulation | ||
| FSH and LH are secreted from the pituitary gland |  |
The follicles grow and produce estradiol. The ovary is stimulated to produce an oocyte. The oocyte is released from the follicle to the fallopian tube. |
| Ovary Fallopian tube |
The “suppression” drug stops the secretion of the LH hormone which is produced from the pituitary gland in the brain and causes ovulation. In this way it’s possible to accurately regulate the time of ovulation.
The stimulation drug includes similar hormones to the ones that are secreted from the pituitary gland in order to stimulate the ovaries to produce follicles. The increase dosage of these hormones leads to the development of multiple follicles instead of single oocyte that matures in the natural cycle.
| IVF cycle | ||
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The women’s own FSH and LH are not secreted from the pituitary gland – they are blocked by the antagonists
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The follicles grow and produce estradiol |
The ovarian response is monitored by ultra-sound scan and blood tests of E2 (estradiol). For the final oocyte maturation a HCG injection is given 36 hours before the programmed egg collection (similar to the naturally occurring LH hormone, which is secreted in the middle of cycle that triggers ovulation).
