Table 1 Main characteristics of included studies in the systematic review and meta-analysis
Study | Country | Study design | No. of cycles | Mean age | Cut-off value | Treatment | Type of embryo transfer | Cycle protocol | Day of EMT measurement | NOS scorea |
|---|---|---|---|---|---|---|---|---|---|---|
Hu 2021 [12] | China | Retrospective cohort | 5220 | 30.2 | 8.0Â mm | IVF/ICSI | Frozen | artificial cycle, natural cycle, ovulation induction cycle | hCG trigger or progesterone initiation day | 9 |
Guo 2020 [10] | China | Retrospective cohort | 3157 | 31.5 | 7.5Â mm | IVF/ICSI | Fresh | GnRH agonist, GnRH antagonist, mild stimulation, natural cycle | hCG trigger day | 8 |
He 2019 [11] | China | Retrospective cohort | 1139 | 30.5 | 8.0Â mm | IVF/ICSI | Fresh and frozen | NA | hCG trigger or progesterone initiation day | 7 |
Borges 2019 [8] | Brazil | Retrospective cohort | 402 | 34.1 | NA | ICSI | Fresh | GnRH antagonist | NA | 8 |
Oron 2018 [17] | Israel | Retrospective cohort | 864 | 32.5 | 7.5Â mm | IVF/ICSI | Fresh | GnRH agonist, GnRH antagonist, natural cycle | hCG trigger day | 7 |
Kaser 2015 [15] | US | Case–control | 199 | NA | 9.7 mm | IVF/ICSI | Fresh and frozen | Fresh: NA Frozen: artificial cycle | NA | 9 |
Chung 2006 [9] | US | Case–control | 435 | 31.9 | 10 mm | IVF/ICSI | NA | NA | The last recorded thickness prior to oocyte retrieval | 7 |
Liu 2021 [20] | China | Retrospective cohort | 9266 | 30.9 | 8.0Â mm | IVF/ICSI | Fresh | GnRH agonist, GnRH antagonist, other | hCG trigger day | 8 |
Huang 2020 [13] | China | Retrospective cohort | 1016 | 30.2 | 7.6 mm | IUI | NA | Letrozole + HMG | hCG trigger day | 9 |
Ribeiro 2018 [18] | Belgium | Retrospective cohort | 939 | NA | 7.0Â mm | IVF/ICSI | Fresh | GnRH antagonist | hCG trigger day | 8 |
Jing 2019 [14] | China | Retrospective cohort | 5251 | 30.9 | 9.0Â mm | IVF/ICSI | Frozen | Artificial cycle, natural cycle | the day before embryo thawing | 9 |
Zhang 2019 [19] | China | Retrospective cohort | 6181 | 32.0 | 8.0Â mm | IVF/ICSI | Frozen | Artificial cycle, natural cycle | hCG trigger or progesterone initiation day | 9 |
Moffat 2017 [16] | Switzerland | Retrospective cohort | 764 | 34.4 | NA | IVF/ICSI | Fresh | GnRH agonist, GnRH antagonist | hCG trigger day | 9 |
Rombauts 2014 [21] | Australia | Retrospective cohort | 4537 | 34.4 | 9.0Â mm | IVF/ICSI | Fresh and frozen | Fresh: GnRH agonist, GnRH antagonist Frozen: artificial cycle, natural cycle | hCG trigger or progesterone initiation day | 8 |
Huang 2021 [23] | China | Retrospective cohort | 1755 | 30.0 | 8.0Â mm | IVF/ICSI | Frozen | GnRH agonist, GnRH antagonist | hCG trigger or progesterone initiation day | 8 |
Liu 2021a [25] | China | Retrospective cohort | 9273 | 31.2 | 8.0Â mm | IVF/ICSI | Fresh | GnRH agonist, GnRH antagonist, other | hCG trigger day | 7 |
Zhang 2022 [28] | China | Retrospective cohort | 13,458 | 30.5 | 8.0Â mm | IVF/ICSI | Frozen | Natural cycle, artificial cycle | hCG trigger or progesterone initiation day | 7 |
Zheng 2022 [29] | China | Retrospective cohort | 4313 | NA | 8.0Â mm | IVF/ICSI | Frozen | Artificial cycle, natural cycle | progesterone initiation day | 7 |
He 2022 [22] | China | Retrospective cohort | 8235 | 29.4 | 7.5Â mm | IVF/ICSI | Frozen | Natural cycle, artificial cycle | hCG trigger or progesterone initiation day | 9 |