Purification of water for in vitro fertilization and embryo transfer

The purpose of this study was to determine whether water obtained from the Milli-Q water purification system (Millipore, Mississauga, Canada) needed further purification for use in in vitro fertilization and embryo transfer. We describe a method for maintenance of the Milli-Q system. To assess water quality, alternate batches of culture media were prepared by using either Milli-Q water or Milli-Q water further treated by twice glass distillation. The percentage of mouse two-cell embryos that developed to blastocysts and the human in vitro fertilization-embryo transfer pregnancy rates were recorded for each batch. There were no significant differences in the parameters examined, indicating that further purification by twice glass distillation is not necessary if the Milli-Q system has been maintained as outlined.