Short gamete co-incubation during in vitro fertilization decreases the fertilization rate and does not improve embryo quality: a prospective auto controlled study.

PurposeEvaluate the effect of short gamete incubation on fertilization rate and embryo quality.MethodsA prospective study has been performed. Two thousand five hundred and forty seven sibling oocytes from 240 couples undergoing IVF attempts were allocated to a short (1 h) or a standard (18 h) insemination procedure. Diploid fertilization rate (two pronuclei, 2PN), polyspermy (>2PN) and embryo quality were compared.ResultsThe fertilization rate was statistically lower in the short insemination group compared to the standard insemination one (64.9% and 70.1%; P = 0.039), with a similar polyspermy rate observed between the two groups. A slight, but non significant, increase was observed concerning good embryo quality rate in the short insemination group when compared to the standard insemination, both at day 2 (60.1 vs. 58.1%; P = 0.06) and day 3 (53.2 vs. 48.5%; P = 0.22).ConclusionThis new study highlights that a 1 h gamete exposure decreases the fertilization rate and does not improve embryo quality compared with a standard 18 h insemination procedure.