Hormonal medications are administered to stimulate the ovaries in such a way that several follicles develop ; does may be adjusted during the cycle depending upon follicles growth. Ovulation induction has several methods, depend on a which method is suitable for each patient according to the physician's judgement. The combination of GnRH-a and gonadotrophins is currently the most frequently used method for timulating the ovaries.

Careful monitoring will prevent the development for too many eggs and will thus reduce the change of multiple pregnancies and the development of the "Ovarian Hyperstimulation Syndrome".

Monitoring can be performed in two ways :

• by endocrine assay of the blood levels of estrogen, LH and progesterone.

• by ultrasound scanning using the modern technique of vaginal ultrasound which does not require the bladder to full. Using ultrasound, a picture of the ovaries, the follicles and the state of the lining of the uretus can be obtained.

When the follicular development has reached the stage when an optimum number of eggs will be produced without untoward effects, hCG will be administered to trigger ovulation. Egg retrieval will be schedule within 34-36 hours after hCG administration.