Routine morphological scoring systems in assisted reproduction treatment fail to reflect age-related impairment of oocyte and embryo quality

Abstract

Routine morphological scoring systems in assisted reproduction treatment are based on parameters that presumably correlate with the biological quality of gametes and embryos, including chromosome abnormalities. Maternal age is a key factor predicting pregnancy and live birth, and it is therefore of considerable interest to identify age-related indicators of oocyte and embryo quality in assisted reproduction treatment. The purpose of this study was to examine whether routine morphological scoring systems reflect age-related impact on oocyte and embryo quality among 4587 couples undergoing their first assisted reproduction treatment. This study assessed over 43,000 oocytes, 25,000 embryos and 7900 transferred embryos and analysed the associations among the following parameters: number of oocytes retrieved, oocyte quality, including maturity, fertilization rates, embryo quality, based on morphological features, and treatment outcome. Advanced chronological age was found to be associated with fewer oocytes retrieved, fewer embryos available for cryopreservation, as well as lower pregnancy, implantation, live birth rates and a higher miscarriage rate. No age-related correlation was found between fertilization rates, oocyte or embryo quality. Routinely-used morphological scoring systems, such as assessment of blastomere count, shape and fragmentation, fail to reflect age-related impact on oocyte and embryo quality.