Table 3.

Summary of randomized trials on the effect of diet during pregnancy on the risk of gestational diabetes mellitus

Ref.	Design	Comparison	No. of participants (studies)	RR of GDM (95%CI)
Song et al[54], 2016	Meta-analysis, 27 RCTs (11487 women)	Lifestyle intervention of diet, PA or both vs standard management	11487 (27)	0.82 (0.70-0.95)
		PA plus diet vs standard management	6047 (14)	0.85 (0.70-1.03)
		Diet only vs standard management	1279 (5)	0.80 (0.58-1.10)
Tieu et al[53], 2017	Meta-analysis, 11 RCTs (2786 women)	Dietary recommendations vs standard treatment	1279 (5 RCTs)	0.60 (0.35-1.04); in overweight and obese women RR 0.39 (0.19-0.79)
		Low-glycemic index (GI) diet vs medium- or high-GI dietary recommendations	912 (4 RCTs)	0.91 (0.63-1.31)
		High-fiber diet vs standard dietary recommendations	25 (1)	No association
Shepherd et al[55], 2017	Meta-analysis, 23 RCTs (8918 women)	Combination of diet and exercise vs standard management	6633 (19)	0.85 (0.71-1.01)
Guo et al[56], 2019	Meta-analysis, 47 RCTs (15745 women)	Lifestyle intervention (diet, exercise, and mixed interventions) vs standard management	15745 (47)	0.77 (0.69-0.87)
		Diet alone vs standard management	2838 (11)	0.75 (0.60-0.95),

RR: Relative risk; PA: Physical activity; RCTs: Randomized clinical trials; CI: Confidence interval; GDM: Gestational diabetes mellitus.