CULTURE AND TRANSFER OF HUMAN BLASTOCYSTS INCREASES IMPLANTATION RATES AND REDUCES THE NEED FOR MULTIPLE EMBRYO TRANSFERS

Objective: To determine whether the transfer of blastocysts on day 5, developed in sequential culture media, resulted in an increase in impl antation rate compared with embryos transferred on day 3. Design: Comp arative study of embryo culture regimes. Setting: Private practice ass isted reproductive technology center. Patient(s): Twenty-three patient s undergoing routine IVF cycles. Intervention(s): Culture of embryos t o day 3 in either standard culture conditions or a serum-free chemical ly defined medium. One hundred one embryos were subsequently cultured from day 3 to day 5 in a second serum-free medium specifically designe d to support development of the blastocyst. Main Outcome Measure(s): E mbryo cell number and quality on day 3. Blastocyst development on day 5. Implantation rate (determined by fetal heart) and ongoing pregnancy rate (PR). Result(s): Implantation rates for embryos transferred at t he blastocyst stage of development were twice that observed for embryo s transferred on day 3, around the eight-cell stage. Significantly mor e embryos were required for transfer on day 3, compared with day 5, to establish similar PRs. Conclusion(s): Viable human blastocysts can be obtained in sequential culture media the in the absence of coculture and serum. Transfer of blastocysts in IVF will facilitate high PRs whi le limiting the number of embryos transferred and therefore minimizes the risk of multiple gestation. (C) 1998 by American Society for Repro ductive Medicine.