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Hum Reprod. 2004 Jul;19(7):1598-603. Epub 2004 May 13.

A prospective, randomized study: day 3 versus hatching blastocyst stage.

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St Luke Clinic, 5, Tsumori-Tomioka, Oita City 870-0947, Japan.

Erratum in

  • Hum Reprod. 2005 Apr;20(4):1119.



Recently, advances in human IVF-embryo transfer (ET) have been reported using sequential media and blastocyst stage ET. In our previous report, using a prospective, randomized study, no advantage was found using the blastocyst stage ET compared with day 3 ET. This study was performed in order to evaluate implantation and pregnancy rates of hatching blastocyst stage ET compared with conventional day 3 ET.


A total of 480 patient cycles were evaluated using a prospective, randomized study. The pregnancy rate and implantation rate were compared between the day 3 ET (n = 240) and hatching blastocyst stage ET (Hat ET; n = 240). The Hat ET group had a pregnancy rate of 29.3% (55 out of 188) and an implantation rate of 21.4% (67 out of 313). The day 3 ET group had a pregnancy rate of 29.2% (70 out of 240) and an implantation rate of 19.1% (93 out of 488). In the Hat ET group, the pregnancy rate, implantation rate and ongoing pregnancy rate of day 5 ET and day 6 ET were all higher than the respective rates in the day 7-9 ET group.


We found that the pregnancy rate and implantation rate of ET with hatching stage blastocysts had no advantage compared with the conventional day 3 ET.

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