Freeze-all indications in women with subfertility undergoing IVF: a cohort study

Abstract

Research question: How widely is the freeze-all strategy implemented in clinical practice, and what are its indications?

Design: This multicentre, prospective observational study included women aged ≥18 years with subfertility and a clinical indication for IVF or intracytoplasmic sperm injection (ICSI) across 24 Spanish assisted reproductive treatment (ART) centres. Patients were included between February 2021 and July 2022, and followed-up until confirmation of pregnancy (ongoing pregnancy, ≥20 weeks) or 6 months after cryopreservation. The primary endpoint was the proportion of patients who cryopreserved all available embryos and the main indications.

Results: The population comprised 1034 evaluable women (mean ± SD age 36.3 ± 4.1 years). The main causes of subfertility were male factor (301/1034, 29.1%) and maternal age (277/1034, 26.8%). Ovarian stimulation with FSH plus highly purified urinary human menopausal gonadotrophin/LH was performed in 466/906 (51.4%) women. For pituitary down-regulation, most women (704/881, 79.9%) received the gonadotrophin-releasing hormone antagonist ganirelix. The freeze-all strategy was indicated in 794 (78.1%) patients, with the most common reasons being planned preimplantation genetic testing (490/794, 61.7%) and risk of ovarian hyperstimulation syndrome (192/794, 24.2%). Of the 709 first embryo transfers analysed, 132 (18.6%) were fresh embryo transfers and 577 (81.4%) were frozen embryo transfers. By the third embryo transfer, the cumulative rates of clinical and ongoing pregnancy per embryo transfer were 72.2% (436/604) and 62.9% (317/504), respectively.

Conclusions: The preferred treatment strategy in the study cohort was to freeze all available embryos, mainly because of planned preimplantation genetic testing and to avoid the risk of ovarian hyperstimulation syndrome.

Keywords: Embryo transfer; Freeze-all strategy; IVF; Ongoing pregnancy rate; Ovarian stimulation.