Bellver 2003.

Methods	Randomised controlled trial Parallel design Single centre Not blind Power calculation: done
Participants	988 women (infertile women n = 605 and donors n = 383) who were all considered to be at risk of moderate or severe OHSS (495 albumin/493 control) > 20 retrieved oocytes was the basic risk factor of OHSS Age (29.9 versus 29.7years) Duration of infertility (not stated) No. of FSH and hMG ampoules (not stated) No. of oocytes (28.7 versus 27.8) No. of embryos (15 versus 19) No. of transferred embryos (2.8 versus 3.0)
Interventions	Study group: 40 g human albumin infused intravenously at a slow rate, immediately after oocyte retrieval Duration: during 30 min Control group: no treatment
Outcomes	Method of diagnosing severe OHSS: criteria for (Golan 1989) Severe OHSS: 25/495 versus 23/493 Pregnancy: 138/298 versus 166/307 Method of diagnosing pregnancy: fetal heart rate Tolerability: yes Safety: yes Cost‐benefit: stated (195 euros/patient)
Notes	Two kinds of GnRH agonist were used and only early OHSS was assessed. Placebo was not used in their control group, which eliminates the placebo effect of albumin administration. Serum E2 level, which was previously reported as an independent risk factor for severe OHSS, was not considered a high‐risk factor in this study
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated
Allocation concealment (selection bias)	Unclear risk	Method not reported
Blinding (performance bias and detection bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	966/988 (98%) randomised women included in analysis
Selective reporting (reporting bias)	Unclear risk	Unclear whether data on adverse events were collected prospectively as it was not a prespecified outcome, though mentioned in the discussion section
Other bias	Low risk	No other potential bias identified