Comparing the clinical pregnancy outcomes of fresh embryo transfer in young patients with poor prognosis using different ovarian stimulation protocols

OBJECTIVE: To evaluate the clinical pregnancy outcomes of fresh embryo transfer at the cleavage stage utilizing gonadotropin-releasing hormone agonist (GnRH-a) and the antagonist protocols in young patients with poor prognosis. METHODS: A retrospective cohort study was carried out on patients who underwent in vitro fertilization-embryo transfer (IVF-ET) between January 2016 and July 2024. Women under 35 years old with anti-Müllerian hormone (AMH) levels < 1.2 ng/ml in fresh cycles were included. A total of 1,732 cycles using the GnRH-a protocol and 3,168 cycles utilizing the antagonist protocol were investigated. The two groups were compared based on their baseline characteristics, clinical and embryological laboratory parameters, and outcome indicators. To compare the clinical results of the two stimulation protocols, we employed propensity score matching (PSM, 1:1) and multivariate logistic regression. RESULTS: After PSM (1:1) with a tolerance of 0.01, the number of cycles in the two groups was 1422 each.The GnRH-a group had a higher clinical pregnancy rate (55.01%, P = 0.003) and live birth rate (41.66%, P < 0.001) than the antagonist group (clinical pregnancy rate: 47.67%; live birth rate: 31.74%). Ectopic pregnancy, early miscarriage, preterm birth, and the number of live births did not differ significantly (P > 0.05). Multivariate logistic regression analysis revealed that the clinical pregnancy rate in the GnRH-a group (OR = 1.25,95%CI:1.02, 1.52) was 1.25 times higher than that in the antagonist group (P = 0.0297), and the live birth rate(OR = 1.38,95%CI:1.12, 1.71) was 1.38 times higher (P = 0.0025). Additionally, compared to the antagonist group (transfer cancellation rate: 45.71%; total embryo freezing: 31.58%), the GnRH-a group exhibited reduced rates of fresh cycle transfer cancellation (34.67%; P < 0.001) and total embryo freezing (22.01%; P < 0.001). The rates of oocyte retrieval cancellation, oocyte retrieval failure, and the lack of usable embryos did not differ significantly between the two groups (P > 0.05). CONCLUSION: In young patients with poor prognosis, the GnRH-a protocol for controlled ovarian stimulation in fresh embryo transfer cycles produces higher clinical pregnancy and live birth rates, as well as a lower fresh transfer cancellation rate, as compared to the antagonist protocol.