Introduction: Considering the important role played by nutrition in pregnancy outcomes weight gain during pregnancy, and overweight/obesity in later life, this study was conducted to assess the weight gain and food consumption patterns in pregnant women of Tehran. Materials and Materials: This study was a cross-sectional study with quota sampling based on the aim (n=265). Data collected by a questionnaire, included two sections: Demographic/socio-economic and 24hour dietary recall, completed by expert interviewers. Mothers’ height and weight were measured and BMI were computed. Pre-pregnancy weight was obtained from the historical files. Statistical analysis was done using Chi-Square, student and paired t-test, Pearson correlation and regression analysis. Results: Of subjects, 57% were normal weight, 15% underweight, 16% overweight and 12% were obese. Mean weight gain in the overweight and obese groups was higher than the recommended level (p<0.01) based on FGP recommendations for pregnant women, they consumed less bread/cereals, and milk/dairy products, and more meat/its alternatives, vegetables, fruits, and sweets/fats. The regression model showed that weight gain during pregnancy increased in the number of children and gestational age and decreased with increase in age and pre-pregnancy BMI. Conclusion: Monitoring weight gain during pregnancy, implementing FGP recommendations and awareness regarding about the proper weight gain are the main strategies for preventing post partum overweight/obesity, especially in obese and older women.