A combination of drugs are used to manipulate the cycle and stimulate the development of mature eggs. A variety of different regimes are used depending on individual requirements.
However, most would include drugs from the following groups: -
1. Gonadotrophin releasing hormone (GnRH) analogue, which has the effect of “switching off” the pituitary’s natural production of FSH and LH. This is important in order to prevent interference with stimulated follicular development. This is given either as a nasal spray or daily injection. Occasionally longer acting injections lasting for a month are used. The analogue stimulates, and then suppresses, activity of a small gland in the brain known as the pituitary, which normally controls the release of the two important reproductive hormones – follicle stimulating hormone (FSH) and luteinising hormone (LH). Essentially, the analogue suppresses the normal link between the pituitary and ovary. These hormones normally stimulate the ovary to produce a single follicle each month but, by using suppression drugs, additional follicles that would normally go to waste, develop.
2. Follicle Stimulating Hormone (FSH) and Human Menopausal Gonadotrophin (HMG) are used at doses between 50 and 450 units to simulate follicular development and are given by daily injection.
3. Human Chorionic Gonadotrophin (HCG) (Pregnyl) is given in the late evening 36 to 40 hours before egg collection. It has the effect of causing the eggs within the follicles to mature, ready for fertilisation. The action is the same as the LH which peaks mid-cycle.
4. After the egg collection, Progesterone support is given in the form of Cyclogest suppositories placed in the rectum. These can be used vaginally after embryo transfer. An alternative preparation is Gestone, an injectable progesterone given on a daily basis. These drugs prepare the endometrium for implantation of the embryo. Occasionally, additional hormone support is provided in the form of HCG injections (Pregnyl).
These preparations may delay the onset of the next period even if you are not pregnant. A pregnancy test should be performed two weeks after the embryo transfer.
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