The effects of brief gamete co-incubation in human in vitro fertilization

Purpose: To investigate whether very short exposure of mature oocytes to sp erm in vitro may affect the fertilization rates, embryo cleavage rates, and embryo quality between sibling oocytes in the same patient. Methods: Sibling oocytes of the same patient from 23 oocyte collection cycl es were randomly allocated to the study group, with a 1-hr or 3-hr sperm-oo cyte incubation, or the control group with the standard overnight gamete co -incubation. The fertilization rates, cleavage rates, and subsequent embryo quality were evaluated. Results: Our results showed no statistically significant differences in fer tilization rates, embryo cleavage rates, and quality of the embryos between the study group and the control group. Conclusions: Since the present study showed that long exposure of the oocyt e to sperm has no advantage over short exposure, we prefer shortening the o ocyte-sperm incubation period for reducing the negative effect induced by n onphysiologically high concentrations of spermatozoa.