Loh 2001.

Methods	Single‐centre, 3‐arm, parallel RCT
Participants	130 women (156 FET cycles) Baseline characteristics were similar in the 2 groups Infertility cause: variety of causes
Interventions	HT group (44 women (52 cycles)) E2 was used in graduated dose (2 mg‐8 mg) until endometrial thickness was ≥ 8 mm Progesterone pessaries for 2 days before FET. E2 and progesterone continued until day 17 post FET Clomiphene group (55 women (67 cycles)) Low‐dose clomiphene HT plus GnRHa group (31 women (37 cycles)) GnRHa then E2 and progesterone (as per HT group)
Outcomes	Clinical pregnancy rate per cycle Endometrial thickness
Notes	The study was an abstract; however, the first author provided some study details but it was still not possible to obtain the pregnancy rate per woman; there were multiple cycles per woman and total number of cycles were not equivalent to number of women randomized.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method used in generating sequence not reported
Allocation concealment (selection bias)	Low risk	Allocation was said to have been concealed using sequentially‐numbered, sealed, opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Reported that intervention providers were blinded to endometrial preparation; however, participants and outcome assessors were not blinded. Non‐blinding of outcome assessors could affect some of the outcome measures
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	There were no reports on attrition or reasons for withdrawal
Selective reporting (reporting bias)	Unclear risk	There was insufficient information to determine whether outcomes were selectively reported
Other bias	Unclear risk	Insufficient information provided to assess possible sources of other bias