A number of drugs are now available to aid the female partner to achieve multiple follicular growth and to bring about ovulation ( the release of the egg from the follicle into fallopian tube ). Some drugs may be taken by oral , by injection or by intranasal spray. There are several methods of ovulation induction depending on each patient. The combination of GnRH-a and FSH is currently the most frequently used methods for stimulating the ovaries. The new and effective drug , GnRH-antagonist , is now also introduced into this kind of treatment.

 Careful monitoring will prevent the development of too many eggs and will thus reduce the chance 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 full bladder. Using ultrasound , a picture of the ovaries , the follicles and the endometrial lining of the uterus can be obtained

When the follicular development has reached the stage of the optimum sizes, hCG will be administered to trigger ovulation. Egg retrieval will be scheduled within 34 - 36 hours after hCG administration.