Controlled ovarian stimulation for in-vitro fertilization.

Controlled ovarian stimulation with gonadotrophins is an essential part of in-vitro fertilization treatment. The aim is to produce an optimum number of oocytes to maximize success in the safest possible way. Pituitary downregulation with a gonadotrophin-releasing hormone agonist and stimulation with recombinant follicle-stimulating hormone is used widely. However, there are many different protocols in use with little evidence to determine the optimum regimen. Markers of ovarian reserve and patient characteristics are used in an attempt to individualize treatment. However, these do not necessarily reflect the quality of the oocytes and resultant embryos. Inadequate doses of gonadotrophins can lead to a poor response resulting in treatment failure. However, higher doses can lead to a hyper response, resulting in ovarian hyperstimulation syndrome which is potentially life-threatening. Both poor and hyper response are associated with reduced pregnancy rates. Various strategies, such as electively freezing all the embryos, are being introduced to optimize outcomes while ensuring patient safety.