Table 1.

Population, intervention/exposure, comparison, outcomes and study design (PICOS) criteria for inclusion of the studies in this systematic review and meta-analysis

Parameter	Definition
Population	Iranian women with gestational diabetes mellitus (GDM)
Intervention/exposure	• Any nutritional factors (including dietary intakes or their biomarkers) as exposure • Nutrition modifications or supplementations
Comparison	• Non-GDM women • GDM women on placebo or control diet
Outcomes	• Development of GDM • Management of GDM considering any maternal and neonatal outcomes related to GDM
Study design	• Observational studies • Interventional studies