ObjectiveTo explore the relationship between the diet during pregnancy and gestational diabetes mellitus (GDM), and analyze the effect of GDM on weight gain, outcome and complication of mother and infant. MethodsWe selected 128 GDM pregnant women and 267 non-GDM pregnant women who were investigated by semi-quantitative food frequency method during September 2009 to March 2011. Then, we collected relevant information and the data were analyzed by t-test and chi-square test. ResultsThere were statistically significant differences between the two groups in total calorie, carbohydrate, fat and protein intakes per day (P<0.05). In general, the rates of insufficient weight gain and excessive weight gain during pregnancy in the GDM group were significantly higher than the non-GDM group (P<0.05), while proper weight gain rate was significantly lower (P<0.01). The risk of hydramnion, intrahepatic cholestasis and pregnancy-induced hypertension in the GDM group was significantly higher than the non-GDM group (P<0.05), while there was no significant difference between the two groups in premature delivery, cesarean section or premature membrane ruptures (P>0.05). Apgar scores were significantly different at minute 1 and 5 between the infants in the two groups (P<0.05). The incidence of fetal death, malformation, mild neonatal asphyxia and fetal macrosomia in the GDM group was significantly higher than the non-GDM group (P<0.05). No significant differences between the two groups in low birth weight infant, cord entanglement and fetal distress were detected (P>0.05). ConclusionGDM can lead to high incidence of poor outcome and complication. It is vital to strengthen the examination and keep balanced dietary structure, in order to reduce the complication and improve the health of mother and child.