JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):166
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263922

P-154. Luteal phase support in frozen embryo transfer (FET) cycles: pregnancy and abortion rates of different protocols and administration routes

Lucas Jorge Borsari¹, Alvaro Pigatto Ceschin¹, Onel Alejandro Amaya Goitia¹, Nathan Ichikawa Ceschin¹, Jhuly Laurentino Nunes¹, Lucileine Keico Nishikawa¹

¹ Feliccita Instituto de Fertilidade - Curitiba - Paraná - Brasil

Objective: Different routes for luteal phase support are available, but the optimal route still is a topic of debate for frozen embryo transfer (FET). In this study, we aim to evaluate three protocols for progesterone administration, comparing the efficacy between them.
Methods: This is a retrospective study from patients who underwent embryo transfer cycles between the years 2021 - 2025. The patients were divided in 3 groups, according to the route of administration of the progesterone: Intramuscular (IM) - 50mg/d, Vaginal - 400mg twice a day or Combined - 400mg twice a day + 50mg on alternate days. The type of endometrium preparation was also analyzed, with two possible cycles: modified natural or artificial cycles. All the patients started the luteal phase support 6 days prior to the FET.
Results: The mean age for patients in this study was 35, and the main causes of infertility were male factor, tubal alterations and endometriosis. There were no significant differences in abortion rates (Combined - 17,5% vs. Vaginal - 21,8% vs. IM - 32,1% - p=0.370), clinical pregnancy rates (Combined - 60,6% vs. Vaginal - 48,7% vs. IM - 50,9% - p=0,21) and live birth rates (Combined - 30.9% vs Vaginal - 20.4% vs. IM - 23.6% - p=0.058). When comparing the Vaginal protocol Vs. Combined protocol, live birth rates (20.4% versus 30.9% - OR 1.74 [0.927 - 3.289]) and abortion rates (21.8% versus 17.5% - OR 0.762 [0.299 - 1.943]) showed no notable differences, but the pregnancy rates (48.7% versus 60.6% - OR 1,625 [0.933 - 2.828]) showing a tendency in favor of Combined group. Despite there being no statistical significance among the previous results, the Combined group showed slightly better rates than Vaginal and IM administration routes.
Conclusion: The combined administration groups showed better absolute results then the other routes, despite no statistical significance. Therefore, further prospective evidence is needed to confirm this finding.