Perinatal and neonatal outcomes of 494 babies delivered from 972 vitrified embryo transfers

Objective: To evaluate the safety of vitrification of embryos by comparing the perinatal outcome of vitrified day 3 ETs with fresh cleavage-stage ETs. Design: Retrospective analysis. Setting: Assisted reproduction center. Patient(s): A total of 806 women with 494 infants delivered were included. Intervention(s): Supernumerary embryos and embryos of patients at risk of ovarian hyperstimulation syndrome were vitrified using a Cryotop carrier in an open system and were transferred after warming. Main Outcome Measure(s): Implantation and pregnancy rates, obstetric outcomes, neonatal outcomes, and congenital birth defects. Result(s): A total of 2,543 vitrified embryos were warmed, and 2,375 survived and were transferred. The implantation, pregnancy, miscarriage, and live birth rates were 26.91%, 47.22%, 6.07%, and 38.58%, respectively. In singletons, the mean birth weight was 3,337.44 g, and the mean Apgar scores were 8.91, 9.85, and 9.89 at 1, 5, and 10 minutes, respectively. In multiple gestations, the mean birth weight was 2,556.45 g, and the mean Apgar scores were 8.90, 9.34, and 9.47 at 1, 5, and 10 minutes, respectively. Only seven congenital malformations were observed among the 494 babies. Compared with fresh cleavage-stage ETs, the mean birth weight in the vitrified group was higher in both singleton and multiple gestations. All the other results were similar between the two groups. Conclusion(s): Compared with fresh ETs, vitrified day 3 ET shows no significant differences in obstetrical and neonatal outcomes. The study suggests that vitrification with Cryotop is an effective and safe method for the cryopreservation of human cleavage-stage (day 3) embryos. (Fertil Steril (R) 2012; 97: 1338-42. (C) 2012 by American Society for Reproductive Medicine.)