Can we use incubators with atmospheric oxygen tension in the first phase of in vitro fertilization? A retrospective analysis

Purpose: Aim of the present study was to compare two culture strategies used in our routine in vitro fertilization program.Methods: This is a retrospective analysis. Two culture systems were used in parallel and analysed retrospectively: 1) Use of atmospheric oxygen tension (~20 %) until insemination followed by use of low (~5 %) oxygen concentration; 2) Exclusive use of low oxygen concentration. Main outcome was the utilization rate defined as the number of transferred + vitrified embryos per inseminated oocytes. Secondary outcomes were clinical pregnancy and live birth rates.Results: A total of 402 in vitro fertilization cycles were analyzed. Demographic and clinical data of patients belonging to the two culture systems were not significantly different. Utilization rate, cumulative clinical pregnancy rate and cumulative live birth rate per cycle was similar using two different oxygen concentration compared to exclusive use of low oxygen tension (37 % versus 39 %; 30 % versus 30 %; 23 % versus 28 %, respectively).Conclusions: The use of a culture system with atmospheric oxygen tension from recovery of oocytes until insemination followed by culture in low oxygen gives results similar to exclusive use of low oxygen concentration.