Received January 23, 2026
Accepted February 18, 2026

Objective: To describe embryological outcomes in oocyte donors undergoing progesterone-primed ovarian stimulation (PPOS) with either recombinant human follicle-stimulating hormone (rhFSH): recombinant human luteinizing hormone (rhLH) (2:1) or highly purified human menopausal gonadotropin (hp-hMG). Methods: Young, healthy donors began PPOS on cycle day 2 and were sequentially allocated into an observational case series study. Donors receive either rhFSH:rhLH (2:1) or hp-hMG (both at 225 IU/day; n = 26 and n = 10 donor cycles, respectively). Final oocyte maturation was triggered with triptorelin 0.2 mg. Retrieved oocytes were fertilized by ICSI, and embryos were cultured to the blastocyst stage and graded. A subset of blastocysts underwent PGT-A biopsy prior to vitrification. The oocyte retrieval team and embryologists were blinded to treatment allocation. Results: Baseline donor characteristics were similar. Donor cycles allocated to rhFSH:rhLH showed numerically higher oocyte yield, metaphase II oocytes, 2PN fertilization, and total blastocyst formation. The mean number of good-morphology blastocysts per cycle was approximately two-fold higher with rhFSH:rhLH (4.5 vs. 2.0). Following an interim descriptive review of the first ten hp-hMG cases showing suboptimal embryological outcomes, further allocation to hp-hMG was discontinued as a programmatic decision. No inferential statistical testing was performed, consistent with the exploratory case series. Conclusion: In this exploratory case series, rhFSH:rhLH within PPOS demonstrated more favorable laboratory outcomes. These results generate hypotheses and support the need for further studies to confirm the observations and determine their clinical relevance in oocyte donation programs.