Baruffi 2000.

Methods	Single centre Unclear if power calculation performed ITT analysis unclear Published as full paper
Participants	103 women from Brazil aged 37 years or less, undergoing ICSI for the first time. Mean zona thickness: control group 17.1 μm (SD 1.7); AH 16.6 μm (SD 2.2). Mean age: control group 31.4 (3.6); AH group 31.8 (3.6)
Interventions	AH (laser; thinning partial; 48 hours egg retrieval to AH; 0 hours AH to transfer), 51 women randomised, 141 embryos transferred versus No AH, 52 women randomised, 149 embryos transferred
Outcomes	Implantation, clinical pregnancy, miscarriage
Notes	No reply No of embryos transferred AH 2.76; Control 2.87
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Women were selected at random, using a randomisation table
Allocation concealment (selection bias)	Unclear risk	No information in the text
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No information in the text
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were no losses to follow up and all women were analysed
Selective reporting (reporting bias)	Unclear risk	Original protocol not viewed. Live birth not reported