Recombinant LH priming improves follicular efficiency and pregnancy outcomes in women with diminished ovarian reserve undergoing antagonist IVF stimulation.

Women with diminished ovarian reserve represent a low-prognosis population in assisted reproduction, in whom improving the efficiency of converting the available antral follicle pool into retrievable oocytes may be clinically relevant. We conducted a retrospective single-center cohort study including 232 IVF/ICSI cycles (232 women) performed between January 2022 and April 2025 in POSEIDON groups 3-4 (anti-Müllerian hormone <1.2 ng/mL), comparing a high-dose antagonist regimen preceded by combined oral contraceptive pretreatment plus recombinant luteinizing hormone priming (150 IU/day for 7 days; LHP, n = 93) with a comparable high-dose antagonist regimen without priming (no-LHP, n = 139). Both groups received fixed high-dose stimulation with recombinant follicle-stimulating hormone (300 IU/day) plus recombinant luteinizing hormone (150 IU/day). The primary outcome was ongoing pregnancy at ≥12 weeks. Cycle suspension before oocyte retrieval was less frequent with LHP than with no-LHP (1.1% vs. 10.1%). Follicular efficiency also favored LHP, with higher follicular output rate (59.4% vs. 52.8%) and follicle-to-oocyte index (82.6% vs. 70.9%). In fresh transfers, ongoing pregnancy was higher with LHP per started cycle (18.3% vs. 9.4%) and per embryo transfer (30.4% vs. 15.5%), with a similar trend per oocyte retrieval (18.5% vs. 10.4%). In multivariable logistic regression analyses, LH priming remained independently associated with ongoing pregnancy after adjustment for age, body mass index, and anti-Müllerian hormone, with consistent effect estimates across models (odds ratio range 2.20-2.41). Combined first-transfer ongoing pregnancy, defined as the fresh transfer or, when no fresh transfer occurred, the first subsequent frozen embryo transfer derived from the same stimulation cycle, also showed a favorable trend (29.7% vs. 17.0%). On updated follow-up, all pregnancies that had reached the ongoing stage in both groups resulted in live birth. In low-prognosis women, a COC-based recombinant luteinizing hormone priming protocol within a high-dose antagonist framework was associated with improved follicular efficiency, fewer pre-retrieval suspensions, and higher ongoing pregnancy rates in fresh cycles. Prospective studies are warranted to confirm these findings and better define patient selection.