Vitrification of Human Oocytes and its Contribution to In Vitro Fertilization Programs

Abstract

To study the cumulative pregnancy outcome, particularly in terms of live births, with the consecutive transfer of embryos from fresh and vitrified/warmed oocytes to infertile patients in a routine infertility program. Patients were initially submitted to in vitro fertilization embryo transfer with fresh embryos, while surplus oocytes were vitrified with the Vitri-Ingá method. Patients who did not succeed to carry their gestation to term underwent a new cycle with embryos from their own warmed oocytes. Some of the patients participating in the first warming cycle, who still possessed surplus oocytes, underwent a second warming cycle. Clinical and pregnancy outcomes obtained with fresh and warming cycles were compared using the chi-square test at a level of significance of 5%. Of the 211 participating patients, 97 (46%) got pregnant with fresh embryo transfer, and 69 (32.7%) carried their pregnancies to term. Of the patients participating in the first and second warming cycles, 32/100 (32%) and 6/20 (30.0%) resulted in live births, respectively. Thus, of the 211 participating patients, 107 carried their pregnancies to term, representing a cumulative live birth rate of 50.7%. No statistically significant differences between the use fresh and vitrified oocytes were found for any of the variables studied. Oocyte vitrification offered the possibility of gestation in more than one attempt after just one controlled hyperstimulation. Apart from alleviating the financial burden on patients, vitrification of oocytes may result in a feasible solution for the problems generated by abandoned frozen embryos.