Therefore, the type of protocol may have a role in the occurrence of this syndrome. However, based on the fact that the clinician chooses the stimulation protocols based on age, AMH levels, the number of antral follicles etc, of the patient,21 it may be more reasonable to conclude that this syndrome could be a manifestation of low ovarian reserve than the GnRH agonist flare protocol. This finding is close to the estimate of some investigators,3,18,20,22 suggesting that genuine EFS could be a variant form of low ovarian reserve. According to the study by Zreik et al,20 poor ovarian response was found in 29% of the stimulated cycles. Various authors argue that the EFS phenomenon could be clarified by premature ovulation, low ovarian reserve, or hCG-related errors.