Abstract: ［Abstract］ Objective〖HTSS〗〓To retrospectively analyze the medical records of fertilization disorders in conventional in vitro fertilization（IVF） and to explore the clinical and laboratory factors that are closely related to complete fertilization failure and low fertilization rate.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓The clinical and laboratory information of conventional IVF cycles from the Second Hospital of Hebei Medical University was retrospectively analyzed. According to the situation of IVF fertilization they were divided into group A(complete fertilization failure, fertilization rate= 0) 56 cycles, group B(low fertilization rate, fertilization rate< 30%) 91 cycles, group C(fertilization rate≥30%) 1 899 cycles. According to the conventional fertilization rate, the rescue intracytoplasmic sperm injection and half intracytoplasmic sperm injection cycles were divided respectively into group A, B and C. The following contents among the three groups were compared. The female age, duration of infertility, basic follicle stimulating hormorne(FSH), luteinizing hormone(LH), estradiol(E2) levels and proportion of primary and secondary infertility and the proportion of causes of infertility were compared. The days of gonadotropin(Gn), Gn dosage, LH, E2, progesterone(P) levels and per eggs E2 level at human chorionic gonadotropin(HCG) injection day and the number of obtained oocytes were compared. The treatment regimen, the proportion of mature eggs, abnormal eggs and the proportion of 1-4 eggs obtained in the three groups were compared. The semen parameters before and after on the day of oocyte retrievaled were compared.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓There were no significant differences in age, basal hormones FSH, LH and E2 levels between groups A, B and C(P＞005). The infertility years, the proportion of primary infertility, male factors and the proportion of unexplained infertility in group A and group B were higher than that in group C, and the differences were statistically significant(P＜005). The proportion of tubal factors in group A and group B was lower than that in group C, and the difference was statistically significant(P＜005). There were no significant differences in the days of Gn, Gn dosage, LH, E2, P level and E2 level per egg at HCG injection day between groups A, B and C(P＞005). The number of oocytes obtained in group A was lower than that in group B and C, and the difference was statistically significant(P＜005). Comparison of treatment protocol among groups A, B and C showed no statistical significance(P＞005). The proportion of oocytes number 1-4 was higher in group A than in group C and B, and the difference was statistically significant(P＜005). The proportions of mature oocytes and abnormal oocytes in the three groups were 46.4%， 60.4%， 89.2% and 16.1%， 8.8%， 0.5%, with statistically significant differences(P＜005). The sperm concentration of group A, B and C on the day of egg collection was lower than that of group C. The sperm motility rate, the proportion of forward motile sperm before treatment and the proportion of Aclass sperm in forward motile sperm in group A were lower than those in group B and C, the differences were statistically significant(P＜005). The proportion of forward motile sperm and the proportion of Aclass sperm in forward motile sperm in group A and B were lower than those in group C after treatment, and the differences were statistically significant(P＜005).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓There are many factors affecting fertilization disorder during IVF fertilization. High risk factors may include primary infertility, longer infertility time, unknown causes and male infertility. Immature oocytes and low semen parameters or poor sperm quality may be associated with the fertilization failure.

Key words: fertilization in vitro, fertilization failure, oocyte quality, sperm parameters