| Author’s name | Study type/Country/Year | Reason for exclusion |
| Kozlowska, A [26] | Prospetive/Poland/2018 | This study focused on multivitamins, including folate. It did not focus in any section on folate as an independent factor that can impact gestational diabetes risk |
| Li, S [18] | Cross-sectional/China/2019 | This study did not measure folate intake. Instead, it used serum folate level to relate to the risk of developing gestational diabetes |
| Barzilay, E [28] | Cohort/Canada/2018 | This study measured serum concentrations of one-carbon nutrients, not folate intake |
| Lai, JS [16] | Cohort/Singapore/2018 | This study tried to link serum concentrations of folate along with other vitamins to the risk of gestational diabetes |
| Araujo, JR | Case-control/Portugal/2012 | This study measured folate uptake by primary cultured cytotrophoblasts isolated from human placentas of patients with gestational diabetes and compared them to controls |
| Reece, EA | Review/USA/2012 | This review did not relate folic acid supplementation to the development of gestational diabetes, but it discussed the protective impact of folate on the risk of neural tube defects |