Mexico 2011.

Methods	'Randomised by a computer programme'; no other information was given (see notes below and risk of bias table).
Participants	386 women at 12 to 28 weeks' gestation were attending for care at the National Institute of Perinatology Isidro Espinosa de los Reyes, Mexico, 116 of whom were included in this review. Settings: National Institute of Perinatology Isidro Espinosa de los Reyes, Mexico.
Interventions	75 g OGTT WHO 1999 criteria, 75 g OGTT ADA 2010 criteria and 100 g OGTT O'Sullivan 1973 criteria.
Outcomes	GDM diagnosis, stillbirth, macrosomia, threat of preterm birth, caesarean and instrumental birth, pregnancy‐induced hypertension, preterm rupture of membranes, oligohydramnios, polyhydramnios.
Notes	Non‐randomised participants included in the group were allocated 100 g OGTT with ADA criteria; therefore this group was not included in any analysis. Study dates: 1 June 2006 to 1 September 2006. Funding sources: not reported; declarations of interest: not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	'Randomised by a computer programme'; no other information was given.
Allocation concealment (selection bias)	Unclear risk	Concealment of allocation was not reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	7/54 (13%) participants allocated 75 g OGTT were unable to complete and were not followed up and included in the analysis.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes seem to have been reported.
Other bias	High risk	The numbers for this trial are unclear. It appears that women > 28 weeks who were not screened or randomly assigned were included in the 100 g OGTT group. Inclusion of non‐randomised participants in 1 of the groups; uneven numbers in the remaining groups, possibly due to the fact that study authors failed to use an intention‐to‐treat design (see notes above regarding loss of participants due to lack of completion of the test); possible 'double' counting of participants in the screened tables; and lack of clarity surrounding the study design suggest that extreme caution should be exercised when results from this trial are interpreted. 35 twin pregnancies were included; however group allocation was not reported, so they may or may not be included in the comparison groups described in this review. We have used data from 2 groups including 116 randomly assigned women.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding of personnel and participants is not reported but is possible because the tests consisted of glucose drinks and could have appeared to be identical. Blood glucose levels, birthweight and ruptured membranes would not have been affected by knowledge of treatment groups, but outcomes such as caesarean birth may have been affected.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of outcome assessors was not reported.