Efficacy of modified natural cycle vs. hormone replacement therapy in oocyte donation for recipients of advanced maternal age: a retrospective study.

Purpose: To compare the efficacy of modified natural cycle (mNC) preparation versus hormone replacement therapy (HRT) for endometrial preparation in recipients of donated oocytes, specifically focusing on pregnancy rates in women of advanced maternal age.

Methods: Retrospective multicenter analysis conducted between 2021 and 2024. It includes 220 cycles of fresh single blastocyst transfers resulting from oocyte donation.