Frozen-thawed blastocyst transfer in natural cycle increase implantation rates compared artificial cycle

Abstract

Objective: To analyze global outcomes in frozen-thawed embryo transfer according to endometrial preparation with natural cycle and artificial cycle taking into account the developmental stage of the embryo.

Methods: Retrospective cohort study, held in a tertiary-care university hospital with 1265 cycles for frozen-thawed embryo transfer of 860 patients, performed between January 2014 and December 2017. A total of 1097 embryo transfers were performed: 163 transfers in natural cycle (N), 531 in artificial cycle: transdermal estrogens and 403 with oral estrogens.

Results: Demographical factors were similar in the three groups studied. When comparing the number of embryos transferred, the quality and the stage of embryos within the three groups there were no differences. Implantation rates were significantly higher in natural cycle. When adjusted depending on the developmental stage, blastocyst embryos transferred in natural cycle preparation had the highest implantation rate. Multiple pregnancies were also higher in natural cycle preparation. There were no significant difference between the groups in the clinical pregnancy rate, ongoing pregnancy, live birth, and miscarriages.

Conclusions: Our results suggest that a natural cycle endometrial preparation assessing the disappearance of the dominant follicle by ultrasound increases implantation rates, especially when transferring blastocysts.

摘要

目的：根据自然周期和人工周期子宫内膜准备, 考虑胚胎的发育阶段, 分析冻融胚胎移植的全局结果。方法：回顾性队列研究, 2014年1月至2017年12月期间在一所三级保健大学医院进行, 共1265个周期, 860例患者的冷冻-解冻胚胎移植。一共进行了1097次胚胎移植：自然周期163次移植（N）, 人工周期531次：透皮雌激素和403人口服雌激素。结果：所研究的三组患者人口学因素相似。当比较移植胚胎数量时, 三组患者胚胎质量和阶段没有差异。自然周期的植入率显着更高。当根据发育阶段进行调整时, 自然周期囊胚移植的植入率最高。自然周期中的多胎妊娠率也较高。组间临床妊娠率, 持续妊娠, 活产和流产方面无显著性差异。结论：我们的结果表明, 通过超声评估优势卵泡消失的自然周期子宫内膜准备增加了植入率, 尤其在囊胚移植时。

The Chinese abstracts are translated by Prof. Dr. Xiangyan Ruan and her team: Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.

Keywords:

• Frozen-thawed embryo transfer
• blastocyst
• natural cycle
• implantation rates
• IVF

Disclosure statement

The authors do not have any conflict of interest to claim.