Can we improve pregnancy rate in GnRH antagonist protocols for IVF?

The recent introduction of GnRH antagonists in assisted reproductive technologies (ART) has simplified ovarian stimulation (1). This is mainly due to the immediate mode of antagonist action, which allows their administration during the follicular phase, when the inhibition of premature LH surge is required. In this way, the prolonged period of downregulation, necessary in the long agonist protocol, can be avoided, while FSH requirement is decreased in terms of total dose and duration (2). Despite the above mentioned advantages, acceptance of GnRH antagonists in IVF, has been hampered by a lower clinical pregnancy rate as compared to the long agonist protocol (2). The difference observed was marginal in terms of clinical importance (5%), however, it has been a source of concern (3) and has stimulated research towards optimizing the existing GnRH antagonist protocols.