Laffoon 1999.

Methods	Single centre, randomised trial
Participants	56 women from North America aged less than 40 years undergoing IVF. Mean age not stated
Interventions	AH (mechanical; complete zona breach; ? hours egg retrieval to AH; ? hours AH to transfer) versus no AH AH: 28 women randomised, embryos transferred not stated Control: 28 women randomised, embryos transferred not stated
Outcomes	Clinical pregnancy
Notes	Attempted to contact author about this study No. of embryos transferred not stated Unclear if power calculation performed ITT analysis unclear Published as abstract
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Timing and method not stated
Allocation concealment (selection bias)	Unclear risk	Allocation concealment unclear
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Participants not blinded or unclear Assessor not blinded or unclear
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	ITT analysis unclear
Selective reporting (reporting bias)	High risk	Published as a conference abstract. Unable to find a full paper publication. Live birth was not reported