Utsunomiya 1998.

Study characteristics
Methods	Single‐centre randomised trial
Participants	55 women from Japan undergoing either ICSI or IVF No data provided on age
Interventions	AH with acid (chemical): 27 women No other details about the day of treatment provided Control: 28 women
Outcomes	Clinical pregnancy rate only (gestation sac on ultrasound)
Notes	No attempt to contact study author No. of ETs not stated Unclear whether power calculation performed ITT analysis unclear Published as abstract only
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation stated but method unclear or incorrect
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 only and did not report on live births
Other bias	Unclear risk	Conference abstract