Abstract:

Objective: To explore the relationship between the number and grade of transferred embryos in fresh cycle and the pregnancy outcome in assisted reproductive technology.Methods: The clinical data of 1 261 cases of fresh transfer cycles were analyzed retrospectively. According to the number of transferred embryos after age stratification were grouped. In women of <35 years, the group A is single embryo transfer and the group B double embryos transfer. In women of ≥35 years, the group a is single embryo transfer the group b double embryos transfer, and the group c three embryos transfer. In each group, patients were further divided into subgroups according to the number of grade Ⅰ embryos transferred. The group A was divided into the group A₀ and the group A₁ (the number of gradeⅠembryos transferred was 0 and 1). Similarly, the group B was divided into group B₀, B₁ and B₂. With the same grouping method, patients aged ≥35 years were divided into subgroups (the group a as group a₀ and a₁; the group b as group b₀, b₁ and b₂; the group c as group c₀, c₁ and c₂). The differences of pregnancy outcome were compared.Results: ①In patients <35 years, the clinical pregnancy rate and implantation rate of group A₁ were significantly higher than those of group A₀ (both P<0.05). The implantation rate, clinical pregnancy rate, multiple pregnancy rate and live birth rate of group B₂ were significantly higher than those of group B₀ and B₁ (all P<0.05). Meanwhile, the clinical pregnancy rate of group B₀ was higher than that of group A₀, the implantation rate of group A₁ was higher than that of group B₁, and the multiple pregnancy rate of group A₁ was lower than that of group B₁ (all P<0.05). There was no significant difference in other indexes among the groups (all P>0.05). ②In patients aged ≥35 years, the implantation rate, clinical pregnancy rate and live rate of group a₁ were significantly higher than those of group a₀ (all P<0.05). The clinical pregnancy rate and live birth rate of group b₁ and b₂ were higher than those of group b₀, the implantation rate of group b₂ was higher than that of group b₀ (all P<0.05). The implantation rate and clinical pregnancy rate of group c₂ were significantly higher than those of group c₀ and c₁. However, the multiple pregnancy rate and live birth rate of group c₂ were higher than those in group c₀ (P<0.05). Meanwhile, the multiple pregnancy rate of group c₂ was significantly higher than that of group b₂ (P<0.05). There was no significant difference in other indexes between the groups (P>0.05).Conclusions: In the fresh embryo transfer cycles, the individualized embryo transfer program should be implemented according to the number and grade of embryos. It is suggested that no more than 2 embryos and no more than 1 embryo of grade Ⅰ should be transferred in patients of any age. The single embryo transfer can not only ensure the clinical pregnancy rate, but also effectively reduce the multiple pregnancy rate for the patients with conditions.

Key words: Embryo transfer, Number of embryo, Embryo grade, Pregnancy, multiple, Age factors, Pregnancy outcome