Table 2.
Study characteristics of the case-control studies (n = 4).
| Author, Year | Study duration | Participant size, country, mean(SD) BMI kg/m2, mean(SD) age years | Type of Exposure, Time of Exposure | Intervention assessment | GDM assessment | Results reported: Odds Ratio or Relative risk (95%CI, p value) or GDM incidence |
|---|---|---|---|---|---|---|
| Asadi et al., 2019 [33] | September 2014 and March 2015 |
n = 278, Iran, Pre-pregnancy weight: (kg) GDM:68.82 ± 13.31 Control:63.02 ± 11.77 Age: GDM:29.00 ± 5.17 Control:27.50 ± 4.92 |
Dietary patterns (Prudent diet-higher intakes of fruits, low-fat dairy, potato, Egg, fish, poultry, nuts, organs meat and red meat), Pre-pregnancy |
Dietary assessment was carried out by using a 67-item validated food frequency questionnaire to evaluate dietary history of participants during the last year | ADA criteria |
Prudent Diet: OR 0.88 (0.44–0.99, 0.01) Western Diet: OR 1.50 (0.74–3.03, 0.2) |
| Chen et al., 2019 [35] | March 1, 2012, and December 30, 2016 | n = 9556, China |
Dietary nutrient patterns (High vitamin intake), One year before conception |
A “vitamin” nutrient pattern was characterized as the consumption of diet rich in vitamin A, carotene, vitamin B2, vitamin B6, vitamin C, dietary fiber, folate, calcium, and potassium. | IADPSG criteria | For every quartile increase in the vitamin factor score during one year prior to conception, the GDM risk decreased by 9%; OR: 0.91 (0.86–0.96) |
| Chen et al., 2020 [34] | March 1, 2012 and December 30, 2016 | n = 9556, China |
Dietary nutrient patterns (High vegetable intake), One year before conception |
A “vegetable” dietary pattern was characterized as the consumption of green leafy vegetables (Chinese little greens and bean seedling), other vegetables (cabbages, carrots, tomatoes, eggplants, potatoes, mushrooms, peppers, bamboo shoots, agarics, and garlic), and bean products (soybean milk, tofu, kidney beans, and cowpea) | IADPSG criteria | For every quartile increase in the vegetables factor score during 1 year prior to conception, the GDM risk lowered by 6%; OR: 0.94 (0.89 to 0.99) |
| Shivappa et al., 2019 [36] | - |
n = 388, Iran, BMI: 27.25 (3.82) (GDM) vs 24.64 (3.32) (non-GDM) Age: 29.64 (4.52) (GDM) vs 29.76 (4.26) (non-GDM) |
Dietary inflammatory index (DII) scores using 147-item food frequency questionnaire (Low DII), 1 year before the dietary assessment at 24–28 weeks of gestation |
DII scores (energy, carbohydrate, protein, total fat, fiber, cholesterol, saturated fat, mono-unsaturated fat, poly unsaturated fat, omega-3, omega-6, trans fat, niacin, thiamin, riboflavin, vitamin B12, vitamin B6, iron, magnesium, selenium, zinc, vitamin A, vitamin C, vitamin D, vitamin E, folic acid, beta carotene, garlic, turmeric, onion, caffeine) | Carpenter and Coustan criteria | Continuous DII: OR 1.2 (0.94–1.54) Categorical DII Tertile 3 vs 1: OR: 2.1 (1.02–4.34) |
SD Standard Deviation, CI Confidence interval, OR Odds Ratio, RR Relative Risk, IADPSG International Association of Diabetes and Pregnancy Study Groups, ADA American Diabetes Association.