Freezing of all viable embryos during an IVF cycle, rather than transferring a fresh embryo, is being adopted in the clinic for multiple reasons, including to reduce the incidence of ovarian hyperstimulation syndrome (OHSS) and to improve birth outcomes for both mother and baby. However, there is concern pregnancy outcomes may be compromised utilising this strategy. In this case controlled study we sought to determine whether a ‘freeze only’ strategy in IVF compromises cumulative pregnancy rates. Controls were matched for age, number of egg collections, insemination type and usable embryos available for transfer and freezing on Day 5 or 6. There was no difference between case group and control for mean maternal age, number of egg collections and number of usable embryos. The pregnancy rates achieved in freeze only cycles were no different to those seen in fresh embryo transfer cycles whether considering pregnancy rate from first embryo transfer or cumulative pregnancy rates.
The results of this study were presented at the 5th congress of the Asia Pacific Initiative on Reproduction (ASPIRE). It was awarded Best Clinical Paper.