“Reverse” Dual Stimulation Has Comparable Efficacy, but Higher Efficiency, than Two Conventional Follicular Phase Stimulations in Poor Responders Undergoing In Vitro Fertilization

Background/Objectives: Dual stimulation starting in the follicular phase allows retrieval of more oocytes than single follicular-phase controlled ovarian stimulation (COS). However, dual stimulation excludes fresh embryo transfer (ET), forcing us to postpone the first ET. If dual stimulation is performed in a reverse way (“reverse”-dual stimulation, R-DS), fresh ET can be performed, potentially reducing the time to pregnancy. The aim of the present study is to investigate reproductive outcomes of R-DS compared to two consecutive COS starting in the follicular phase (2FP-COS). Methods: A retrospective study was performed on 146 poor responders matching Bologna criteria, among which 45 underwent R-DS and 101 received 2FP-COS. In the R-DS group, the first COS began 5 days after ovulation and the second 5 days after oocyte retrieval. The primary outcome was the time to pregnancy. Results: In R-DS, stimulation length, retrieved oocytes, and blastocyst formation rate were comparable in the luteal and follicular COS rounds. Circulating progesterone was always