Effectiveness of 2-step (consecutive) embryo transfer. Comparison with cleavage-stage transfer
Goto, S.; Takebayashi, K.; Shiotani, M.; Fujiwara, M.; Hirose, M.; Noda, Y.
Journal of Reproductive Medicine 48(5): 370-374
2003
ISSN/ISBN: 0024-7758 PMID: 12815912 Document Number: 553598
OBJECTIVE: To evaluate the effectiveness of 2-step (consecutive) embryo transfer (ET), in which two cleaved embryos are transferred on day 2 (first step of ET) and a single blastocyst is transferred on day 5 (second step, of ET) in comparison with conventional day 2 ET. STUDY DESIGN: Observational comparative study at different time periods. Subjects were those who had gtoreq4 embryos on day 2 after oocyte retrieval. Those in the conventional group (n=60) received conventional day 2 ET, in which 3 cleaved embryos were transferred on day 2 between January 1999 and June 2000. Those in the 2-step group (n=124) received 2-step embryo transfer, in which 2 cleaved embryos were transferred on day 2 and a blastocyst was transferred on day 5 between September 2000 and February 2002. Patients who planned to receive 2-step ET but could not proceed to the second step of ET because of failure to produce blastocysts were included in the 2-step group. RESULTS: The ongoing pregnancy rate with 2-step ET (51.6%) was significantly higher than with conventional ET (26.7%) (P<.01). The clinical pregnancy rate and implantation rate in conventional and 2-step ET were 30.0% vs. 59.7% and 11.1% vs. 27.8%, respectively (P<.001). CONCLUSION: Two-step ET may benefit patients who can obtain a sufficient number of embryos.