Objective To assess the the efficacy of luteal support with GnRH agonist in patients undergoing IVF in antagonist-based hcg triggered cycles compared with standard luteal support with progesterone.

Design prospective randomized controled study Subjects Patients who underwent antagonist-based cycles performed in the "Shaare Zedek Medical Center" IVF clinic between 2020 and 2022 Intervention Intranasal GnRH-agonist or vaginal Progesterone for luteal support.

Main outcome measures Pregnancy and clinical pregnancy rates, ohss.

The study cohort included 150 patients who underwent 164 cycles. A total of 127 cycles were included. Of them, 64 were treated with GnRH-a and 63 with progesterone.

Hypothesis: This RCT suggests that GnRH-a for luteal phase support is associated with a higher positive β-hCG pregnancy rate and clinical pregnancy rate, compared with standard progesterone support in an antagonist-based protocol triggered with hCG, while maintaining a similar safety profile.

Inclusion Criteria:Criteria for inclusion were patients aged between 18-45 years, BMI between 19-35, infertility diagnosis of male factor, tubal factor, anovulation, unexplained and age-related. Patients with or without infertility diagnosis, who underwent IVF for PGT were also included.

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Exclusion Criteria:

Exclusion criteria were triggering with agents other than hCG, previous 3 or more failed cycles in which a good quality embryo or embryos were transferred, endometriosis, hydrosalpinx, hypogonadotropic hypogonadism, and Mullerian malformations. Drop-out criteria included no fresh embryo transfer, intolerance to GnRH-a, and nasal congestion during the luteal phase.

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