Impact of oocyte aging on early stages of embryo development and effectivity of ART.
Anastasia Koval (RU), Nina Sesina (RU), Ksenia Krasnopolskaya (RU)
[Koval] Engelhardt Institute of Molecular Biology, [Sesina] International Clinic "Family", [Krasnopolskaya ] Moscow Regional Research Institute of Obstetrics and Gynecology
Context: Due to the peculiarities of oogenesis, oocyte age corresponds to the woman age. It is not clear whether the age-related changes in oocytes could affect the early stages of embryo development during the ART treatment. Objective: To analyze the influence of aging on the pregnancy rate, embryological parameters, and early reproductive losses in patients using ART. Methods: Retrospective study in groups, divided according to patient age: less than 30, 30 - 35, 36 - 39, 40 and over years old. Patients: 1734 women underwent IVF/ICSI treatments and 687 women underwent vitrified embryo transfer (January 2015 to September 2016). Interventions: Controlled ovarian stimulation, conventional IVF, embryo culture, embryo transfer. Main Outcome Measures: Number of oocytes collected, fertilization rate, the rate of blastocysts on day 5 of embryo development, clinical pregnancy rate. Results: As expected, clinical pregnancy rate for patients aged under 36 years was significantly higher than for patients 36 years or older (native cycles: 36% vs 26% in 36-39 years group and 12% in 40 and older years groups; P <0.001). For patients up to 40 years old the clinical pregnancy rate was significantly higher in cryo-cycles (12% native vs 27% cryo; P <0.05). However, analysis of the number of oocytes collected, fertilization rate, the rate of blastocysts on day 5 of embryo development, and early reproductive losses did not reveal significant differences between the groups for patients of all ages (P> 0.1). Conclusions: Analysis revealed no changes in embryological parameters between groups despite the decline in pregnancy rates in women aged over 36 years. Influence of age-related changes can, however, manifest in the reduction of embryos' potential for implantation, as evidenced in patients older than 40 years when comparing clinical pregnancy rate in native and cryo cycles.