Meta-analysis finds no difference in pregnancy outcomes when using the ERA

Researchers in a 2022 study performed a meta-analysis to combine the results of 8 ERA studies and found no differences in live birth, pregnancy and miscarriage rates among women who performed the ERA or didn’t.

The endometrial receptivity array (ERA, see here for more information) is a technique commonly used to identify the optimal time for embryo transfer.

Arian et al. (2022), in their systematic review and meta-analysis, combined the results of 8 studies that examined the use of the ERA between 2018 and 2022. A total of 831 women performed the ERA compared to 1,953 who didn’t. Five of the studies were retrospective, one was a randomized controlled trial, one was a prospective cohort study and one didn’t include this information.

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No difference in ongoing pregnancy or live birth rates in women using the ERA

Based on 5 studies and 1,977 participants, there was no statistically significant difference in ongoing pregnancy and live birth rates in women who performed the ERA vs those who didn’t (42.2% vs 37.5%, odds ratio [95% CI]: 1.38 [0.79-2.41]). There was significant heterogeneity (I2 = 83%).

Ongoing pregnancy and live birth rates in women who used the ERA or didn't

No difference in clinical pregnancy rates in women using the ERA

Based on 7 studies and 1,977 participants, there was no statistically significant difference in clinical pregnancy rates in women who performed the ERA vs those who didn’t (53.0% vs 52.0%, odds ratio [95% CI]: 1.14 [0.70-1.85]). There was significant heterogeneity (I2 = 80%).

No difference in miscarriage rates in women using the ERA

Based on 5 studies and 1,009 participants, there was no statistically significant difference in miscarriage rates in women who performed the ERA vs those who didn’t (14.8% vs 10.5%, odds ratio [95% CI]: 1.03 [0.46-2.32]). There was significant heterogeneity (I2 = 71%).

No differences in ongoing pregnancy or live birth rates after ERA when grouped by number of previous embryo transfers

The ERA may be beneficial for women with recurrent implantation failure, so the researchers compiled studies that involved women who had ≤2 or >2 previous failed transfers as a subgroup analysis. They found no differences in either the ≤2 group (3 studies, odds ratio 1.09 [0.72-1.66]) or the >2 group (2 studies, odds ratio 1.81 [0.36-8.98]).

Conclusions

This study found no differences in ongoing pregnancy and live birth rates, clinical pregnancy rates or miscarriage rates in women who performed the ERA compared to those who didn’t. Studies that compared women with ≤2 or >2 previous failed transfers also showed no benefit with the ERA.

The main limitation of this meta-analysis is that the majority of the studies included were retrospective. There was also a large amount of heterogeneity due to differences in the ERA procedures performed by each study.

More well designed randomized controlled trials must be conducted in order to determine the impact of the ERA on pregnancy outcomes.

Reference

Arian SE, Hessami K, Khatibi A, To AK, Shamshirsaz AA, Gibbons W. Endometrial receptivity array before frozen embryo transfer cycles: a systematic review and meta-analysis. Fertil Steril. 2023 Feb;119(2):229-238. doi: 10.1016/j.fertnstert.2022.11.012. Epub 2022 Nov 19. PMID: 36414088.

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About Embryoman

Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.