【Abstract】 Objective To investigate the relationship between Day 3 embryo quality and mitochondria
DNA(mtDNA)copies in embryo culture medium. Methods From July 2017 to October 2018, 93culture media of transferred embryos from 67 patients who accepeted assisted reproductive technology in
School of Medical and Life Sciences/Reproductive & Women-Children Hospital, Chengdu University of
Traditional Chinese Medicine were selected to assessed mitochondria DNA copies by digital polymerase
chain reaction (PCR) technology. According to the cleavage embryo grading criteria, embryos were divided
into good quality group (n=54) and poor quality group (n=39), normal development rate group (n=67) and abnormal development rate group (n=26), high score group (n=72) and low score group (n=21), respectively.The differences of mtDNA copies, female age, body mass index (BMI), basic endocrine condition andclinical outcome were analysed by t-test or ranks test. Results All the other conditions were nonsignificant except mitochondria DNA copies between groups. The mitochondria DNA copies in embryoculture media of good quality group was significant higher than poor quality group [(1.30±1.99 ) vs(0.91±0.94), P<0.05], normal development rate group was significant higher than abnormal development rategroup [(1.28±1.86) vs (0.78±0.71), P<0.05]. But there was no significant difference between both the highscore group and the low score group of the mitochondria DNA copies in embryo culture media [(1.13±1.76)vs (1.15±1.15) copy/μl, P>0.05]. Conclusions Assessing mitochondria DNA copies by digitalPCR technology in the Day 3 embryo culture medium, in combination with morphological grading,may be a novel, non-invasive, sensitive method to evaluate embryo quality. Good quality and normaldevelopment rate embryo could secrete higher mitochondria DNA copies into embryo culture media.