Gonadotropin-releasing hormone (GnRH) antagonists have been widely used for the prevention of premature luteinizing hormone (LH) surges during controlled ovarian hyperstimulation (COH) for in vitro fertilization and embryo transfer (IVF-ET) since the late 1990's.

Many years have passed since GnRH antagonists were introduced to prevent premature LH surges during stimulated cycles. However, there is still no consensus on the optimal GnRH antagonist protocol. Attempts at modifying GnRH antagonist protocols have been made to improve COH outcomes. However, a meta-analysis of 27 randomized controlled trials, including recent reports, showed significantly lower clinical ongoing pregnancy rates in the antagonist group. Thus, additional efforts are needed to identify the optimal stimulation protocols to achieve better follicular and embryonic development and to improve the pregnancy rates in COH using GnRH antagonist.

Given the assumption of a detrimental effect of GnRH antagonist on the pregnancy rate, with current protocols, we hypothesized that a shorter duration of GnRH antagonist administration might improve outcome.

Inclusion Criteria:

• Both ovaries present with no morphological abnormalities
• Normal ovulatory cycle with cycle lengths of between 25 and 35 days
• Basal serum FSH (day 3) level of < 15 mIU/mL
• Body mass index (BMI) ranging between 18 and 27 kg/m2

Exclusion Criteria:

• History of a poor ovarian response
• Evidence of endocrine abnormalities, such as, hyperprolactinemia, thyroid dysfunction, or polycystic ovary syndrome
• Hydrosalpinx
• Severe endometriosis (stage III-IV)