Study quality assessment and data extraction
Two independent reviewers (ER and MC) assessed the study quality and extracted the data
using pre-designed forms. We assessed the risk of bias [16] in the following domains: sequence
generation, allocation concealment, blinding, incomplete outcome data and selective reporting.
Data were extracted in 2x2 tables for dichotomous outcomes. For continuous outcomes we extracted
data on mean and standard deviation for both the groups. When more than one definition
was used for GDM in a study, we extracted data for outcomes using the most recent
diagnostic criteria. Any discrepancies were resolved by discussion with the third reviewer (ST).