Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer

Abstract

Elective cryopreservation of all embryos has been the most effective means to avoid developing ovarian hyperstimulation syndrome (OHSS). However, it is still unknown which stage is optimal for freezing and transferring into uterus in OHSS-risk patients. This study was undertaken to evaluate whether OHSS-risk patients could benefit from transferring blastocysts. A total of 162 women were allocated to cleavage-stage embryo transfer (ET) (group A = 70) and blastocysts transfer (group B = 92) on the basis of patients’ voluntary in their first frozen cycles. Although the mean number of transferred embryos in group A was significantly more than those in group B (2.37 ± 0.52 versus 2.11 ± 0.52, p < 0.05), the clinical pregnancy rates, implantation rates and live birth rates in group B were significantly higher than those in group A (47.83% versus 31.43%, p < 0.05; 31.44% versus 18.67%, p < 0.05; 40.21% versus 27.14%, p < 0.05), and the multiple pregnancy rates in both groups were comparable (34.09% versus 36.36%, p > 0.05). The observed results in OHSS-risk population allow us to take a position in favor of blastocyst transfer, thus pregnancy and live birth could be achieved with fewer ETs and in a shorter time frame.

Chinese abstract

选择性胚胎冷冻保存是避免卵巢过度刺激综合征（OHSS）发生的最有效措施。然而，尚不清楚OHSS高危患者在那一阶段进行胚胎冷冻和移植入子宫是最优的。本研究的目的是为了评估OHSS高危患者是否能从囊胚移植中获益。在自愿的基础上，共有162名女性在第一个冷冻周期被分为卵裂期胚胎移植组（ET）（A 组= 70）和囊胚期移植组（B组 = 92）。尽管A组平均胚胎移植数目明显多于B组（2.37 ± 0.52 与2.11 ± 0.52, p<0.05），然而B组患者的临床妊娠率，着床率和分娩率却明显高于A组（47.83% 与31.43%, p<0.05; 31.44%与18.67%, p<0.05; 40.21% 与27.14%, p<0.05），多胎妊娠率两组相似(34.09% 与36.36%, p>0.05)。在OHSS高危人群中观察到的结果使我们更倾向于采取囊胚期移植，短期内因ETs而妊娠和分娩可能会减少。

• Blastocyst transfer
• cleavage-stage embryo
• first frozen cycle
• OHSS-risk patients

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article. This study was supported by the Program for Zhejiang Leading Team of S&T Innovation, P.R. China (2011R50013) and grants from Wenzhou Municipal Science and Technology Fund of China (Y20100205).