Objective: Compare the effectiveness of the IVF extended embryo culture day 4 versus day 2.
Design: Retrospective analysis.
Setting: Assisted Reproduction centre Apolinar, Department of Obstetrics and Gynecology, 1st Faculty of Medicine, Charles University and General Faculty Hospital in Prague.
Methods: We compared pregnancy rate (PR) and implantation rate (IR) of all IVF and IVF/ICSI embryo transfers (ET) performed between August 2004 and July 2008, in which 2 embryos were transfered. All transfers were done by the same physician. Maternal age was < or = 35 years (from 22 to 35 years, mean 30.4 years, median 31.1 years). The group of embryos evaluated and transfered on the day 2 was compared with the embryos evaluated and transfered on the day 4. Based on the evaluation, each embryo was assigned to one of the following categories: Grade A (top quality embryo) or grade B (medium quality embryo).
Results: On the day 2, ET of A+A embryos led to PR 69.0%; A+B 53.3% and B+B 36.4% (IR 50.0%, 40.0% and 22.7%), where number of transfers was 42, 30 and 11 in every group. On the day 4, ET of A+A embryos led to PR 54.3%, A+B 48.7%, B+B 26.6% (IR 45.6%, 34.6%, 13.3%), where number of transfers was 46.39 and 15 in every group.
Conclusion: In our group, we found no statistical significant difference (p < 0.05) in PR between day 2 and day 4 embryotransfers. Results of the day 2 transfers have a trend to be better than results of day 4 transfers. Regardless of the transfer day, the prognosis of grade A embryos was significantly better (p < 0.05) than for grade B embryos.