The main reasons for unsuccessful blastocyst culture are: decline in ovarian function, woman’s age, poor endometrial status, and abnormality of the embryo itself. 1. Decline in ovarian function: the decline in ovarian function increases the release of pituitary follicle-stimulating hormone and luteinizing hormone, which affects the quality of egg cells. 2. Too old woman: after the woman is over 35 years old, the chance of successful blastocyst culture decreases, the older the woman is, the lower the success rate is, and the success rate of blastocyst culture after 35 years old is only about 50%. 3. Poor endometrial condition: the environment of uterine cavity is not good, the endometrium can not accommodate the blastocyst to adhere and penetrate in the uterus and implant, resulting in unsuccessful blastocyst culture. 4. Chromosomal abnormality of embryo: chromosomal abnormality of embryo caused by various reasons will affect the culture of blastocyst. Unsuccessful blastocyst culture suggests timely consultation and seeking professional guidance from doctors.