Hellebaut 1996.

Methods	Randomised, single centre trial
Participants	120 women from Belgium undergoing IVF or ICSI Mean age: control group 30.8 (3.9); AH group 30.9 (4.3) years
Interventions	AH (mechanical; complete zona breach hole; 48 hours egg retrieval to AH; 0.2 hours AH to transfer) versus no AH AH: 60 women randomised, 168 embryos transferred Control: 60 women randomised, 162 embryos transferred
Outcomes	Implantation, clinical pregnancy, live birth, miscarriage, ectopic pregnancy
Notes	Attempted to contact author about this study. A reply including much useful additional information was received No. of embryos transferred: AH 2.8 (0.6); Control 2.7 (0.6) Unclear if power calculation performed ITT analysis unclear Published as full paper
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	By computer on day of transfer
Allocation concealment (selection bias)	High risk	Allocation concealment inadequate
Blinding (performance bias and detection bias) All outcomes	High risk	Participants not blinded Assessor not blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	ITT analysis unclear
Selective reporting (reporting bias)	Low risk	Live birth reported. Authors responded to requests for details. No other evidence of bias, all outcomes stated were reported