[Extended embryo culture in IVF does not improve pregnancy rate]

Compare the effectiveness of the IVF extended embryo culture day 4 versus day 2.

Retrospective analysis.

Assisted Reproduction centre Apolinar, Department of Obstetrics and Gynecology, 1st Faculty of Medicine, Charles University and General Faculty Hospital in Prague.

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).

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.

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.