An official journal of the Society for Biology of Reproduction and the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn

November 2010 (No. 3)

The culture of human cleavage stage embryos alone or in groups: effect upon blastocyst utilization rates and implantation

Itziar Rebollar-Lazaro 1,2, Phillip Matson 2,3

2 Hollywood Fertility Centre, Nedlands, Western Australia,

3 School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Western Australia, Australia

The effect of cleavage-stage group culture (CGC; embryos cultured in groups of three or more for the first 3 days and then individually to blastocyst) was compared to extended single embryo culture (ESC; embryos cultured individually to the blastocyst stage). While implantation and ongoing pregnancy rates were similar between groups, the blastocyst utilization rate (number of blastocysts suitable for freezing and thawing/total number of embryos cultured to Day 5 and 6) was significantly higher when embryos were cultured in CGC for women <35 yrs thereby increasing the number of embryos available for clinical use for the younger women. This strategy of group culture to Day 3 would seem an ideal protocol to capitalize on an overall embryo quality in two particular settings, namely programmes wishing to (i) undertake Day 3 transfers, and (ii) keep embryos separate from Day 3 to Day5/6 for the purposes of selection. The culture system can also be applied to the embryos of older women without adverse effect, enabling the same system to be used for all embryos.

Reproductive Biology 2010 10 3: 227-234.

1 Corresponding author: Hollywood Fertility Centre, Hollywood Private Hospital, Monash Avenue, Nedlands, WA 6009, Australia; e-mail: