Blastocyst culture and transfer: a step toward improved in vitro fertilization outcome.

OBJECTIVE: To evaluate the efficacy of blastocyst culture and transfer in human in vitro fertilization (IVF) as compared to day 3 embryo transfer. DESIGN: Prospective randomized trial. SETTING: Private assisted reproduction unit. PATIENT(S): A total of 162 IVF patients were included in the day 3 embryo transfer (n = 82) and blastocyst transfer (n = 80) groups. INTERVENTION(S): Embryo transfer on day 3 after culture in the standard culture media and blastocyst transfer on day 5 or 6 after culture in the sequential culture media. MAIN OUTCOME MEASURE(S):Implantation and pregnancy rates, multiple gestation rate. RESULT(S): The implantation rate for embryos transferred at the blastocyst stage was significantly higher than that for embryos transferred on day 3 (26% vs. 13%). The viable pregnancy rate was similar in both groups (29% vs. 26%). Significantly fewer embryos were required for transfer at the blastocyst stage compared with day 3 embryo transfer (2.0 +/- 0.1 vs. 3.5 +/- 0.63). The high-order multiple gestation rate was significantly less with the blastocyst transfer than with the day 3 embryo transfer (4% vs. 19%). CONCLUSION(S): With the use of blastocyst culture, a few embryos can be transferred without decreasing the overall pregnancy rate. This may reduce multiple gestations and improve human IVF outcome.