Effect of pre-IVF incubation in maturation medium on oocyte maturity,fertilization,embryonic development,and clinical outcomes following embryo transfer

Objective:Collected human cumulus-oocyte complexes(COCs)are usually inseminated after 4 to 6 hours in in vitro fertilization(IVF)laboratories.The purpose of this study was to determine the effect of short-term pre-IVF incubation in culture medium on subsequent oocyte maturation,fertilization,and embryonic development,as well as clinical outcomes.Methods:Sixty patients were divided randomly into 2 groups,pre-IVF incubation for 5 hours:1)with(+)the designed oocyte maturation medium;2)without(-)the designed oocyte maturation medium(transferred directly to fertilization medium for 5 hours before insemination).Oocyte maturation and fertilization were assessed,and the rate of cleavage and good quality embryos were evaluated between the 2 groups on days 2 and 3,respectively.Blastocyst development was based on the remaining number of embryos on day 3,continuously cultured to day 5 after embryo transfer or frozen on day 3,and was compared between the 2 groups.Clinical pregnancy,implantation,and miscarriage rates were also compared.Results:Oocyte maturation rates did not differ between groups(85.8±14.1%vs.90.7±9.1%).However,the range of oocyte maturation rates(58.3%-100.0%)for each patient was significantly higher in the(-)group than in the(+)pre-incubation group(71.4%-100.0%).There were no differences in fertilization rates(89.9±10.0%vs.86.5±12.2%)and good quality embryos(70.8±19.1%vs.62.1±23.7%)between groups;however,the blastocyst development rates were significantly different between groups(73.1±20.1%vs.58.8±18.2%,P<0.05).Nevertheless,clinical pregnancy(62.5%vs.61.1%)and implantation(46.9%vs.47.2%)rates did not differ between groups.Conclusions:These results indicate that a short pre-IVF incubation time in the designed culture medium promotes oocyte maturation and embryonic development,suggesting that short pre-IVF incubation of COCs in the designed culture medium may be important for subsequent final oocyte maturation and early embryonic development.