Jelinkova 2002.

Methods	Single centre, randomised trial
Participants	255 IVF participants only; at least 2 previous failures Age AH: 32.3 (4.24), control: 32.1 (3.16) Germany
Interventions	AH (chemical removal by acid, complete zona breach) AH: 128 women Control: 127 women
Outcomes	Clinical pregnancy rate, implantation rate
Notes	Attempted to contact author about this study No. of embryos transferred: AH 2.2; Control 2.2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation stated, but method and timing unclear
Allocation concealment (selection bias)	Unclear risk	Unclear, no details
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Participants not blinded or unclear
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not stated
Selective reporting (reporting bias)	High risk	Protocol not viewed, outcomes were reported on but do not include live birth