Hagemann 2010.

Study characteristics
Methods	Randomised single‐centre cross‐over trial
Participants	103 women in the United States younger than 38 years of age with any embryo with zona pellucida thickness > 13 μm and more than 2 previously failed IVF cycles Mean age: 32.1 years in hatched group, 31.2 in unhatched group
Interventions	AH performed by acidic Tyrode's solution AH: 49 women Control: 54 women
Outcomes	Clinical intrauterine pregnancy rate, implantation rate, spontaneous pregnancy loss, live birth rate
Notes	Power calculation: study states it has inadequate power. Study as ultimately performed had sufficient statistical power to identify only a 30% absolute effect size with alpha = 0.05 and beta = 0.80 ITT analysis unclear Published as full paper
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Randomisation was performed by IVF lab staff by drawing 1 of 200 opaque envelopes from a box
Allocation concealment (selection bias)	Unclear risk	Opaque envelopes drawn but not numbered
Blinding (performance bias and detection bias) All outcomes	Low risk	Study arm to which participants belonged was blinded to caregivers, with the exception of IVF embryologists, as well as to participants
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear
Selective reporting (reporting bias)	High risk	Live birth reported (but results not included in this study, as results were given only for both cycles combined, not for just the first cycle; these are the data we are using). No other evidence of reporting bias
Other bias	Low risk	None identified