ABSTRACT
In the case of assisted reproductive techniques namely, stimulated intrauterine insemination (SIUI) and in vitro fertilization (IVF), the aim of gonadotropin therapy is to completely override the endogenous feedback mechanisms and induce multifollicular rather than monofollicular growth. The key to this is maintaining a subthreshold level of gonadotropins during the time of follicular recruitment thus overriding the process of selection of a single dominant follicle. Patients undergoing multifollicular stimulation for IVF or intra cytoplasmic sperm injection (ICSI) also receive a concomitant gonadotropin-releasing hormone (GnRH) agonist, or more recently antagonist to block endogenous leutinising hormone (LH) production and LH surges. Finally when an appropriate follicular size is observed on ultrasound monitoring, final maturation of the follicles is achieved with exogenous human chorionic gonadotropin (hCG) administration. Detailed discussion of the use of gonadotropins in SIUI and IVF follows below.
