Abstract: ［Abstract］ Objective〖HTSS〗〓To explore the application value of blastocysts derived from poor quality embryos on day 3(D3) through its blastulation rate and high quality blastocyst formation rate.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Three hundred and seventyfour in vitro fertilizationembryo transplantation were divided into two groups with blastulation or not after further culture of poor quality embryos on D3. Women′s age, insemination methods, estradiol on the day of human chorionic gonadotropin injection and the number of mature oocytes were also analyzed.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The blastulation rate of 1 938 D3 poor quality embryos from 374 patients was 49.1%(952/1 938) and the high quality blastocyst formation rate was 30.4%(590/1 938). The blastocyst formation rate of patients low than 35 years old was 50.7%(875/1 727) and the high quality blastocyst formation rate was 31.6%(546/1 727), which was statistically higher than the patients more than 35 years old 36.5%(77/211), 20.8%(44/211). In vitro fertilzation blastulation rate and high quality blastocyst formation rate was significantly higher than intra cytoplasmic sperm injection blastulation rate: 51.2%(694/1 356) vs 43.0%(136/316), high quality blastocyst formation rate:33.0%(447/1 356) vs 25.6%(81/316). Patients who have more mature oocytes and much higher estradiol on the day of human chorionic gonadotropin injection, they would have more blastocyst and high quality blastocyst. The clinical pregnancy rate after transplanted the blastocysts came from D3 poor quality embryos was 42.5%, which was significantly lower than the blastocysts from D3 high quality embryos(57.5%).
〖HTH〗〖WTHZ〗Conclusion〓〖HTSS〗Further culture of D3 poor quality embryos can increase the utilization ratio of patients oocytes and decrease the costs of treatment. But according to the patient′s age, the mode of fertilization, the basal endocrine level, the number of mature eggs and other conditions, the utility value and application effect of non quality embryo continuous culture are not the same.

Key words: reproductive techniques, blastula, pregnancy rate