Cumulative birth rates following cryopreservation of all embryos in stimulated in vitro fertilization (IVF) cycles

Abstract

Objective: To cryopreserve all good-quality embryos available after IVF is one way to avoid an impending hyperstimulation and a more attractive alternative to a couple than cancellation of the cycle. At Sahlgrenska University Hospital this method has been practiced since 1991. The aim of this study was to assess the success rate (defined as childbirth per couple) after IVF treatment including one stimulated cycle, resulting in cryopreservation of all good-quality embryos available, followed by replacement of frozen/thawed embryos in one or more natural cycles.

Design: A cohort of 32 women undergoing one stimulation for IVF between January 1991 and December 1993 where all good-quality embryos were cryopreserved and transferred in a later spontaneous cycle were studied retrospectively. The cumulative childbirth rate per couple was calculated.

Results: A total of 28 women underwent a total of 45 transfers with frozen-thawed embryos. In 4 women no transfer has taken place so far. The clinical pregnancy rate per embryo transfer was 33% (15/45) and per patient 54% (15/28). Three spontaneous abortions occurred giving a cumulative childbirth rate per patient of 39% (11/28). In addition, 6 out of the 28 women still have embryos left in the freezer.

Conclusion: Cryopreservation of all good-quality embryos available after IVF is a highly effective alternative to cancellation of a cycle when there is impending hyperstimulation. The use of this approach results in a cumulative childbirth rate per couple of at least 39%. Since only one stimulation was performed, it also seems to be cost effective.