ABSTRACT
In the initial years of IVF the natural cycle IVF had been the protocol, resulting in an extreme delay in the achievement of the rst birth. One of the main reasons was that, in the majority of cycles, a premature luteinizing hormone (LH) surge was noticed and thus, during the oocyte pick-up, no egg could be retrieved. The same was true even with the initiation of ovarian stimulation with urinary gonadotropins. The pregnancy results were still below 10%, as in many cycles only a few oocytes were retrieved or of poor quality due to premature LH surges. Some years later, a huge improvement in the IVF efcacy was observed by the introduction of the concept of hypophysis down regulation using gonadotropin releasing hormone (GnRH)-analogues (1). The main role of GnRH analogues was to achieve functional hypophysectomy and prevent premature LH surges. The above described down regulation was rst achieved with the use of a GnRH-agonist, resulting in a signicant decrease of incidence of such LH surges (2). In respect, an increase of successful oocyte pick-ups with many oocytes was observed, leading to a noticeable increase of pregnancies.
