Abstract
The purpose of this case–control study was to compare implantation, pregnancy, and live birth rate of cryopreserved embryos with that of fresh embryos. A total of 1,488 assisted reproductive technology (ART) trials including 188 cryopreserved embryo replacement trials were reviewed. After proofing the exclusion criteria, 112 patients undergoing a cryopreserved embryo replacement (study group) were matched with 112 patients undergoing a fresh embryo transfer (control group). Matching was done for age of patients, number, and quality of embryos (Day 5 embryos). Data concerning maternal characteristics, survival rate of warming procedure, implantation, pregnancy, ongoing pregnancy, and live birth rates were collected. A lower implantation rate was found for cryopreserved embryo replacement compared to transferring fresh embryos. Live birth rate was found to be equal in both groups.