Wright 2006.

Methods	Single‐centre parallel RCT
Participants	175 women (194 FET cycles) Inclusion criteria: women with functioning ovaries either normo‐ovulatory or oligo‐ovulatory who had surplus embryos frozen following IVF or ICSI and women who had elective freezing of all embryos following OHSS Exclusion criteria: oocytes recipients Number of transferred embryos: HT group 1.77 ± 0.57, FSH group 1.66 ± 0.56 Baseline comparison: similar including age, day 3 FSH and % of ICSI cycles
Interventions	HT group (88 women (94 cycles)) Oral E2 2 mg twice daily from day 1 of cycle. On day 9 or 10 of cycle started US and hormonal assay. Once endometrial thickness was > 7 mm started vaginal micronised progesterone (100 mg in morning and 200 mg in evening) and continued oral E2. If endometrial thickness was < 7 mm switched to vaginal E2 2 mg/d then as above. E2 and progesterone continued on same dose after FET and in pregnant women it was stopped at 8th gestational week FSH group (87 women (100 cycles)) Recombinant FSH 150 U on days 6, 8 and 10 of cycle. US and hormonal assay started on day 9 or 10 and until the endometrium was > 7 mm with a follicle of 16 mm‐20 mm then recombinant HCG was given Vaginal progesterone 100 mg in morning and 200 mg in evening was started in the day following HCG. FET was performed 48 h post progesterone initiation in embryos frozen on day 2 and 72 h in embryos frozen in day 3. Progesterone was continued till 8th gestational week
Outcomes	Clinical pregnancy per cycle Cycle cancellation rate per woman Endometrial thickness
Notes	Contacted first author but she was unable to provide more data, particularly the pregnancy rate per woman
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Process involved in random sequence generation not reported
Allocation concealment (selection bias)	Unclear risk	Methods used in concealing the allocation not reported
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not reported whether participants or personnel (or both) were blinded; non‐blinding of outcome assessors could have influenced some of the outcome measures.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Although reasons for missing data were the same in both groups, numbers of missing outcome data were not balanced between groups.
Selective reporting (reporting bias)	Low risk	All the prespecified outcome measures in the methods section were reported.
Other bias	Low risk	No other potential source of within‐study bias found

ART: assisted reproductive technology; BMI: body mass index; E2: 17 β‐estradiol; ET: embryo transfer; FET: frozen‐thawed embryo transfer; FSH: follicle‐stimulating hormone; GnRHa: gonadotrophin releasing hormone agonist; HCG: human chorionic gonadotrophin; HT: hormone therapy; ICSI: intracytoplasmic sperm injection; IM: intramuscular; ITT: intention to treat; IU: international unit; IVF: in vitro fertilisation; LH: luteinising hormone; OHSS: ovarian hyperstimulation syndrome; OI: ovulation induction; PGD: preimplantation genetic diagnosis; RCT: randomized controlled trial; SC: subcutaneous; US: ultrasound.