BMJ

Frozen vs. fresh: Embryo transfer in women with low prognosis for IVF

February 26, 2025

For live birth rate, fresh embryo transfer may be a better choice for women with a low prognosis for IVF, compared with a freeze-all strategy. Treatment strategies that prevent fresh embryo transfers, such as accumulating embryos with back-to-back cycles or performing routine preimplantation genetic testing for aneuploidy, warrant further studies in women with a low prognosis for IVF.

Study details: This pragmatic, multicenter, randomized trial was conducted at nine academic fertility centers in China, and included 838 women with a low prognosis for IVF treatment defined by ≤9 oocytes retrieved or poor ovarian reserve (antral follicle count <5 or serum anti-Müllerian hormone level <8.6 pmol/L). Eligible participants were randomized 1:1 to undergo frozen embryo transfer or fresh embryo transfer on the day of oocyte retrieval. Participants in the frozen embryo transfer group had all of their embryos cryopreserved and underwent frozen embryo transfer later. Participants in the fresh embryo transfer group underwent fresh embryo transfer after oocyte retrieval.

Results: In an intention-to-treat analysis, rate of live birth was lower in the frozen embryo transfer group than in the fresh embryo transfer group (32% vs. 40%). The frozen embryo group had a lower rate of clinical pregnancy than the fresh embryo group (39% vs. 47%). Cumulative live birth rate was lower in the frozen embryo transfer group compared with the fresh embryo transfer group (44% vs. 51%). No difference was observed in birth weight, incidence of obstetric complications, or risk of neonatal morbidities.

Source:

Wei D, Sun Y, Zhao H, Yan J, Zhou H, Gong F et al. Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial. BMJ 2025; 388 :e081474 doi:10.1136/bmj-2024-081474. https://www.bmj.com/content/388/bmj-2024-081474