Received November 17, 2013
Accepted November 17, 2013

OBJECTIVE: To assess embryo quality and clinical results obtained with different incubation times before insemination by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles with embryo transfer on day 5. METHODS: We retrospectively studied 1441 assisted reproduction cycles performed between 2008 and 2012, including IVF and ICSI procedures with embryo transfer on day 5. These were separated according to the hours of culture of the oocytes before insemination, as shown below in the table. RESULTS: no significant differences in pregnancy rates or blastocyst formation between the study groups. However, no significantdifference in the fertilization rate, being the group <3 hours, lower than other. CONCLUSION: Preincubation time before IVF / ICSI has no effect on embryonic development and clinical outcome.