Higher success rates in thawed embryo transfer during natural cycle after cryopreservation of all fresh embryos

Abstract

It is well known that transfer of cryopreserved-thawed embryos during a natural or a programmed cycle yields an excellent pregnancy rate. We therefore cryopreserved all embryos three or four days after oocyte retrieval (8cell∼morulla stage), thawed them when needed, and then maintained them in an in-vitro culture for one day prior to uterine transfer.