GnRH agonists vs antagonists.

Gonadotropin-releasing hormone (GnRH) agonists were introduced in ovarian stimulation for in-vitro fertilization to suppress the premature surge of luteinizing hormone (LH). Although agonist use is accompanied by a series of disadvantages, including hypoestrogenaemia, cyst formation, a requirement for a prolonged period of downregulation, and an increase in follicle-stimulating hormone (FSH) and LH as soon as the agonist is administered, agonists became well accepted in clinical practice as their use was also associated with increased rates of pregnancy. However, the recent development of side-effect-free GnRH antagonists, characterized by an immediate mode of action and a shorter period of administration. Provides clinicians with flexibility in terms of administration, and offers patients a friendlier method of ovarian stimulation. Comparative studies between the two analogues have suggested that the use of antagonists is associated with a shorter duration of FSH stimulation and a decreased incidence of hospital admission due to the occurrence of ovarian hyperstimulation syndrome, while the probability of a live birth does not depend on the type of analogue used.