The Effects of Brief Gamete Co-incubation in Human In Vitro Fertilization

Purpose: To investigate whether very short exposure ofmature oocytes to sperm in vitro may affect the fertilizationrates, embryo cleavage rates, and embryo quality betweensibling oocytes in the same patient.Methods: Sibling oocytes of the same patient from 23 oocytecollection cycles were randomly allocated to the study group,with a 1-hr or 3-hr sperm—oocyte incubation, or the controlgroup with the standard overnight gamete co-incubation.The fertilization rates, cleavage rates, and subsequentembryo quality were evaluated.Results: Our results showed no statistically significant differencesin fertilization rates, embryo cleavage rates, andquality of the embryos between the study group and thecontrol group.Conclusions: Since the present study showed that long exposureof the oocyte to sperm has no advantage over shortexposure, we prefer shortening the oocyte—sperm incubationperiod for reducing the negative effect induced bynonphysiologically high concentrations of spermatozoa.