Abstract
In thawed embryo transfer cycles, the most common method is to transfer the embryos after 2 h of culture. Clinical outcomes of frozen-thawed cleavage embryo transfer cycles regarding the embryos status and the culture time of frozen-thawed cleavage embryos were limited and did not elucidate all unclear issues. The objective of this study was to examine the clinical outcomes of frozen-thawed cleavage embryo transfer cycles according to the embryos status and the culture time (2 h or overnight). In this retrospective study (5-year period), 1,654 frozen-thawed embryos were analyzed. Firstly, frozen-thawed cleavage embryos were divided into 2 groups according to their status as follows: with at least 1 optimal embryo and without optimal embryos. Secondly, both of them were divided into 2 groups according to the culture time (2 h or overnight). Age of the female, infertility factors, clinical pregnancy, implantation rate, and live birth rate were compared. There were no statistically significant differences in the pregnancy rate, the implantation rate, live birth rate, the miscarriage rate, and the ectopic pregnancy rate in each group. However, the implantation rate increased after 2 h of incubation (41.1%) compared to overnight incubation (36.0%) in the group with at least 1 optimal day-3 embryo (p < 0.05). The cancellation rate in the suboptimal day-3 embryos group (9.1%) was higher than in the group containing at least 1 optimal embryo (0.2%) for the long (overnight) culture (p < 0.05). The implantation rate can be improved in the optimal day-3 embryos transferred after 2 h of culture, but not for suboptimal day-3 embryos. Some unnecessary transfers can be avoided after overnight culture because of no further cleavage of the embryos.
Highlights
The first human pregnancy from a frozen embryo was achieved using a slow freezing protocol in 1983.1 Since an increasing proportion of pregnancies are conceived after frozen embryo transfer (FET).[2,3] Embryo cryopreservation can help reduce multiple birth rate following assisted human reproduction and can maximize the effectiveness of the in vitro fertilization (IVF) cycles.[4]
There was no significant difference between the groups regarding age, body mass index (BMI) as well as basal follicle-stimulating hormone (FSH), and estradiol (E2) levels (p > 0.05) (Table 1)
In group A2, 1 FET cycle was canceled because no further cleavage was observed, so the total number of transfers was 531
Summary
The first human pregnancy from a frozen embryo was achieved using a slow freezing protocol in 1983.1 Since an increasing proportion of pregnancies are conceived after frozen embryo transfer (FET).[2,3] Embryo cryopreservation can help reduce multiple birth rate following assisted human reproduction and can maximize the effectiveness of the in vitro fertilization (IVF) cycles.[4]. We wondered whether the post-thaw culture time should vary according to the embryo quality before freezing. In thawed embryo transfer cycles, the most common method is to transfer the embryos after 2 h of culture. Clinical outcomes of frozen–thawed cleavage embryo transfer cycles regarding the embryos status and the culture time of frozen–thawed cleavage embryos were limited and did not elucidate all unclear issues
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
