Oral GnRH Antagonist (Linzagolix) Versus Injectable GnRH Antagonist in Controlled Ovarian Stimulation for In Vitro Fertilization: A Randomized Controlled Non-Inferiority Trial With a Concurrent Comparator Cohort Undergoing Progestin-Primed Ovarian Stimulation (PPOS)

This is a single-center, prospective, randomized, controlled non-inferiority trial with a concurrent non-randomized comparator cohort, conducted at CENTRO AMBRA. Women eligible for a GnRH-antagonist protocol are randomized 1:1 to oral linzagolix or the injectable GnRH antagonist using a computer-generated permuted-block randomization sequence (block size of 4, no stratification); allocation is concealed until treatment initiation. A separate, concurrent cohort of women with a clinical indication for PPOS is enrolled as a non-randomized comparator; because assignment to this cohort reflects clinical criteria, it may differ systematically from the randomized arms - confounding by indication limited to the PPOS comparison. This is addressed through pre-specified multivariable adjustment and, where sample size permits, propensity-score methods; the PPOS comparison is interpreted as an association, the randomized comparison as supporting non-inferiority. As treatment is known to investigators and patients, there is no masking (open-label); oocyte and embryo assessment follows standardized, predefined procedures. A target of 40 participants per group (120 total) was defined based on the pre-specified non-inferiority margin of 2.0 MII oocytes. All participants undergo a routine clinical follow-up visit 5 days after oocyte pick-up."

• Ganirelix ; Cetrorelix (Drug): Ganirelix Type: Drug Group: B Description: Ganirelix acetate 0.25 mg administered by daily subcutaneous injection, per fixed or flexible protocol according to center practice, to suppress the premature LH surge during controlled ovarian stimulation. Cetrorelix Type: Drug Arm: B Description: Cetrorelix acetate 0.25 mg administered by daily subcutaneous injection, per fixed or flexible protocol according to center practice, to suppress the premature LH surge during controlled ovarian stimulation.
• Medroxyprogesterone Acetate ; Micronized Progesterone (Drug): This is a non-randomized, concurrently enrolled comparator cohort (not part of the 1:1 randomization). Medroxyprogesterone Acetate - Type: Drug - Arm: C - Description: Medroxyprogesterone acetate 10 mg/day administered orally from stimulation day 1-2 through the day of trigger, as part of a progestin-primed ovarian stimulation (PPOS) protocol with mandatory freeze-all strategy. Micronized Progesterone - Type: Drug - Arm: C - Description: Micronized progesterone 100-200 mg/day administered orally from stimulation day 1-2 through the day of trigger, as part of a progestin-primed ovarian stimulation (PPOS) protocol with mandatory freeze-all strategy.
• Linzagolix (Drug): Description: Linzagolix Type: Drug Group: A Description: Linzagolix 200 mg administered orally once daily, started per center protocol (fixed stimulation day or upon appearance of the dominant follicle) and continued through the day of trigger. Investigational off-label use for suppression of the premature LH surge during controlled ovarian stimulation.

Primary outcomes

• Number of Mature (MII) Oocytes Retrieved [At oocyte retrieval, approximately 36 hours after trigger (first study cycle)]: Number of metaphase II (mature) oocytes collected at oocyte retrieval. Non-inferiority of linzagolix versus the injectable GnRH antagonist will be concluded if the lower bound of the 95% confidence interval for the adjusted mean difference in MII oocytes (adjusted for ovarian reserve, age, BMI, gonadotropin type and dose, and trigger type) excludes a loss greater than the pre-specified non-inferiority margin of 2.0 MII oocytes. An exploratory comparison with the PPOS cohort is also performed, adjusted for baseline confounders.

Secondary outcomes

• Incidence of Premature LH Rise [From initiation of LH-suppressive treatment to the day of trigger (up to approximately 12 days)]

Sex: Female, ages: 18 Years to 42 Years

Inclusion Criteria:

* Female, aged 18 to 42 years
* Indication for IVF/ICSI with controlled ovarian stimulation at CENTRO AMBRA
* Population unselected for ovarian reserve (normal, poor, and high responders are eligible)
* Written informed consent, including consent for off-label use of linzagolix and for data processing
* For the two antagonist arms (Linzagolix and Injectable GnRH Antagonist): acceptance of randomization

Exclusion Criteria:

* Known contraindications or hypersensitivity to the study drugs
* Uterine pathology relevant to the study outcome (e.g., uterine malformations, significant submucosal fibroids)
* Contraindications to pregnancy or to ovarian stimulation
* Concurrent participation in another interfering interventional study