Antinori 1999.

Study characteristics
Methods	Randomisation stated but method unclear Allocation concealment unclear Unclear if single centre/multi‐centre Unclear whether participants and assessors were blinded Unclear whether power calculation performed ITT analysis unclear Published as abstract
Participants	341 women from Italy undergoing IVF. Subgrouped by previous IVF experience: (a) without previous IVF experience (n = 199) or (b) with more than 6 previous IVF failures (n = 142) Mean age: control group 27.0, AH group 27.5 years
Interventions	AH (laser; complete zona breach; unclear how long from egg retrieval to AH; unclear how long from AH to transfer) ‐ 169 women randomised, 221 embryos transferred (estimated) vs Control ‐ no AH ‐ 172 women randomised, 247 embryos transferred (estimated)
Outcomes	Clinical pregnancy, miscarriage, multiple pregnancy
Notes	No reply No. of embryos transferred: AH 2.3, control 2.4
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation stated but method unclear
Allocation concealment (selection bias)	Unclear risk	Unclear; no details provided
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Unclear whether participants and assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No evidence of post‐randomisation exclusions but timing of allocation unclear
Selective reporting (reporting bias)	Unclear risk	Protocol not viewed. Not sure if these are all planned outcomes
Other bias	Unclear risk	Conference abstract