Table 1.
Basic characteristics of included studies
| Author year | Study period | Study design | PCOS diagnostic criteria | Participants | Age, year | BMI, kg/m2 | HRT protocols | Stimulated protocols | Number of embryo transferred | Time of embryo transferred |
|---|---|---|---|---|---|---|---|---|---|---|
| Li Li 2021 | 2017–2020 | retrospective | 2003 Rotter- dam criteria | 1234/200 | HRT 29.6 ± 3.1; rFSH 29.7 ± 2.9 | HRT 23.7 ± 3.9; rFSH 23.7 ± 3.9 | Estradiol valerate 4 mg QD from day 2/3 for 5 days followed by estradiol valerate 6 mg QD 6–8; vaginal supplementation with progesterone 90 mg daily were added days when the endometrial thickness reached 7 mm and the serum progesterone level was below 1.5 ng/mL | Gonarfen (37.5–75 IU) QD from day 5; triggered by hCG (5000 IU) or recombinant hCG (250 μg) | 1 or over | Cleavage stage embryos |
| Jie Zhang 2021 | 2010–2018 | retrospective | 2003 Rotter- dam criteria | 1168/1259 | NA | NA | Estradiol from day3; when the endometrial thickness was 7 mm, exogenous progesterone supplementation was provided | Letrozole, 5 mg QD from day 3 to day 7; in case of a dominant follicle < 14 mm on day 10, a low dosage of hMG was supplemented with incremental doses of 37.5 IU if needed; triggered by hCG | 1 or over | Cleavage stage embryos/blastocysts |
| Nardin Aslih 2021 | 2016–2018 | retrospective | NA | 80/25 | HRT 33.4 ± 5.3; letrozole 35.2 ± 5.3 | HRT 28.0 ± 5.6; letrozole 30.0 ± 7.4 | Estradiol 2 mg TID from day 3 for at least 8 days; on day 8 progesterone (oral dydrogesterone 10 mg TID or vaginal micronized progesterone 100 mg TID or micronized progesterone gel 90 mg BID) was started when endometrial thickness was more than 8 mm | Letrozole, 2.5 mg BID from day 5 to day 9; triggered by 250 mcg recombinant hCG | 1 | Cleavage stage embryos/blastocysts |
| Azadeh Hosseini-Najarkolaei 2020 | 2018–2020 | ART | 2003 Rotter- dam criteria | 59/57 | HRT 29.45 ± 0.42 vs. 30.12 ± 0.33 | HRT 26.10 ± 0.48; letrozole + hMG 25.70 ± 0.46 | Estradiol valerate 4 mg QD for 3 days and then 6 mg QD; on day 7 of estradiol administration, progesterone 50 mg QD IM for 2 or 3 days | Letrozole, 2.5 mg BID from day 3 to day 7 and hMG 75–150 nIU QD from day5 to day9; triggered by 1000 IU hCG | 1 or 2 | Cleavage stage embryos |
| Yuanyuan Man 2020 | 2014–2017 | retrospective | 2003 Rotter- dam criteria | 1224/88 | HRT 28 (26–31); HMG 28 (26–30) | HRT 24.43 (21.81–27.31); HMG 24.66 (21.38–28.73) | Estradiol valerate 4 mg QD from day 2/3 for 5 days followed by estradiol valerate 6 mg QD for 5 days; 5 days before blastocyst transfer oral dydrogesterone 30 mg QD was started | hMG 37.5/75 IU QD from day3/5; triggered by 4000–8000 IU hCG | 1 or 2 | Blastocysts |
| Jie Zhang 2019 | 2011–2016 | retrospective | 2003 Rotter- dam criteria | 850/1236 | HRT 29.07 ± 3.32 vs. 28.95 ± 3.27 | HRT 23.34 ± 3.68; letrozole + hMG 23.11 ± 3.62 | oral 17b-E2 2 mg TID from day2/3; when endometrium thickness over 7 mm, vaginal progesterone 400 mg QD were taken | Letrozole, 5 mg QD from day 3 to day 7; in case of a dominant follicle < 14 mm on day 10, a daily dosage of 75 IU hMG was supplemented with incremental doses of 37.5 IU if needed; triggered by 5000 IU hCG | 1 or 2 | Cleavage stage embryos/blastocysts |
| Lee KH 2017 | 2014–2015 | retrospective | NA | 119/45 | NA | NA | 6 mg estradiol valerate from day3 + 50 mg; progesterone, IM | Letrozole, 5 mg QD from day 3 to day 7 | NA | Cleavage stage embryos |
| Jian Mei Yu 2015 | 2010–2012 | retrospective | 2003 Rotter- dam criteria | 273/262 | HRT 30.51 ± 3.35 vs. 30.48 ± 3.34 | HRT 22.74 ± 2.09; hMG 22.58 ± 2.17 | Estradiol valerate 2 mg BID from day3; progesterone 40 mg IM when endometrium thickness reached at 8 mm | hMG 75 IU QD from day 5 to day9; on day 10, the dose was increased in 75–150 IU for 5–10 days when needed; triggered by 5000–10,000 IU hCG | 1 or over | Cleavage stage embryos |
| Yan Jun Hu 2014 | 2011–2012 | retrospective | 2003 Rotter- dam criteria | 76/40/32 | HRT 28.9 ± 3.0 vs. 30.1 ± 3.7 vs. 28.7 ± 4.1 | HRT 22.6 ± 2.5; letrozole 22.8 ± 2.0; hMG 22.5 ± 2.3 | Oestrogen 2–4 mg QD for 5–7 days followed by 4–6 mg QD for 5–7 days; progesterone 80 mg QD was commenced when the endometrium thickness reached at 8 mm | Letrozole group: letrozole, 5 mg QD from day 3 to day 7; hMG 75 IU were added if the follicular diameter was less than 14 mm on day10 with dose increments of 37.5 IU every 5–7 days when needed; triggered by 10,000 IU hCG. hMG group: hMG 75 IU QD from day 3; on day 10, the dose was increased in 37.5 IU for 5–7 days when needed; triggered by 10,000 IU hCG | 1 or over | Cleavage stage embryos |
NA not available