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Posted by on Oct 17, 2020 in Infertility | 0 comments

In a nutshell

This study compared natural cycle (NC) or hormone replacement cycle (HRC) in terms of fertility outcomes in women undergoing frozen embryo transfer (fzET). 

They found that fertility outcomes were similar with NC or HRC. 

Some background

Assisted reproductive technology (ART) is used to treat infertility. ART includes procedures like in vitro fertilization (IVF). One of the steps in IVF is transferring an embryo into the uterus (womb). This can be done with a fresh embryo or with a frozen one. Frozen embryo transfer (fzET) has several benefits such as embryos can be transferred when the endometrium (EM; the lining of the uterus) is thick enough. This supports the growing fetus. 

During a natural cycle (NC) the EM becomes thick. This is caused by natural hormones. Some women may have hormonal issues and not produce a thick EM. Hormone replacement cycles (HRC) can be used to increase the EM thickness. It is unclear if NC or HRC are associated with better fertility outcomes in women undergoing fzET. 

Methods & findings

This study included 174 women that underwent fzET. All women had 2 previous cycles of failed HRC. Women were separated into 2 groups. 98 women underwent fzET with a NC and 76 women underwent another HRC before fzET. 

On the day of EM transformation, the EM thickness was higher in the NC group compared to the HRC group. However, there was no difference in pregnancy rates, miscarriage rates, or live birth rates between the 2 groups.

The bottom line

The authors concluded that there was no difference in fertility outcomes between NC and HRC during fzET.

The fine print

This study was based on medical records data. Women were not randomly assigned to NC or HRC. This could bias the results. 

Published By :


Date :

Sep 11, 2020

Original Title :

A comparison of pregnancy rate between natural cycle and hormone replacement cycle in patients who underwent frozen embryo transfer using 2 consecutive hormone replacement regiments: A STROBE-compliant retrospective study.

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