The purpose of this study is to compare the efficacy of two controlled ovarian stimulation protocols, the GnRH agonist protocol, widely known as the "long" protocol, and the flexible GnRH antagonist protocol, in terms of pregnancy rates and embryological data, in infertile patients receiving IVF treatment.

The formulation of controlled ovarian stimulation protocols is one of the primary reasons for the successful development of IVF. The "long" GnRH agonist protocol, also known as the gold standard, has been widely used with considerable success. More recently, on the other hand, GnRH antagonist provide a new promising approach for endogenous gonadotrophin suppression by blocking the GnRH receptor. There is conflicting data in the literature regarding the relative merits of the two ovarian stimulation protocols.

COMPARISON: Pregnancy rates and embryological data will by assessed in IVF patients treated with either the "long" GnRH agonist (Arvekap) or the flexible GnRH antagonist (Ganirelix) protocol.

Inclusion Criteria:

• Age 18-39 years
• Body mass index 18-29 kg/m2
• Menstrual cycle from 24-35 days
• Normal basal FSH (<10 IU/ml)
• Normal basal LH (<10 IU/ml)
• Normal basal estradiol (<80 pg/ml)

Exclusion Criteria:

• Poor responder patients
• Polycystic ovaries