Iacobelli 2008.

Methods	Prospective, randomised controlled trial
Participants	792 participants undergoing ICSI treatment. Inclusion criterion was a maternal age below 40 years and exclusion criterion was the complete absence of mature oocytes. Number of cycles per patient and previous treatments are unclear.
Interventions	Oocytes and embryos were cultured in 6% CO2 and 21% O2 or in 6% CO2, 5% O2 and 89% N2. Timing of embryo transfer unclear.
Outcomes	Embryo development and quality, fertilisation rate, implantation rate, clinical pregnancies. Outcomes were reported as percentages.
Notes	Location: Italy Setting: European Hospital Group sizes unclear Study published as conference abstract Funding unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation has not been described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Length of follow up unclear, loss to follow up unclear and ITT analysis unclear
Selective reporting (reporting bias)	Low risk	All outcomes mentioned on the method section are reported in the result section
Other bias	Unclear risk	Embryo transfer policy unclear