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

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

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.

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.

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.