Freezing all embryos – rather than transferring a fresh embryo to the uterus during the same cycle in which the eggs were collected and freezing the rest – benefits older IVF patients, a new study has found.
The "freeze-all" approach was developed to help minimise the risk of ovarian hyperstimulation syndrome (OHSS) in high risk patients.
It also helped to address concerns that the drugs used for ovarian stimulation during IVF may have a negative impact on the uterine receptivity of some patients.
A study presented at the Annual Meeting of the European Society of Human Reproduction and Embryology in Helsinki, Finland, demonstrates that there is strong evidence that freeze-all protocols offer significantly improved IVF outcomes, particularly among women over the age of 35, with successes recorded at 46% in freeze-all compared with 33% in fresh cycles.
Dr Karen Hunter Cohn from Celmatix, a US-based company working in fertility and women’s health, and her team studied more than 16,000 IVF treatment cycles performed at 12 leading fertility centres in the USA.
The freeze-all IVF strategy also benefitted all women with elevated progesterone levels prior to egg retrieval, but a diagnosis of polycystic ovarian syndrome, endometriosis, tubal disease, or unexplained infertility had no significant impact on the effect of freeze-all transfers.
Dr Eric Widra from Shady Grove Fertility in Washington DC, USA, one of the researchers, said that interest in a freeze-all approach to IVF is growing.
"There are several reasons clinics do freeze-all cycles," he said.
"These include patients at high risk for OHSS, patients having preimplantation genetic diagnosis prior to embryo transfer, and importantly, those patients who have a premature rise in the concentration of progesterone hormone prior to egg retrieval. Several studies have shown that this rise in progesterone is associated with a lower pregnancy rate after fresh embryo transfer.
"The evidence of this study is intriguing, but without prospective randomisation, we cannot yet conclude that this is an effective strategy for any group of patients."
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