OBJECTIVE: To investigate the association between socio-demographic factors and dietary patterns in pregnancy. METHODS: Cross-sectional study with baseline data from a cohort of 421 postpartum women aged 18 and 45 years resident in Rio de Janeiro, Brazil. Dietary intake was evaluated with a validated food frequency questionnaire at 15 days following delivery, having as time frame the second and third pregnancy trimesters. Dietary patterns were identified using factor analysis for principal components analysis. The association between socio-demographic factors and the identified dietary patterns was assessed with multiple linear regression analysis. RESULTS: Two dietary patterns were identified: i) healthy: fruits; green vegetables; vegetables; fish; roots, corn and potato; milk and dairy and herbal tea mate, and negatively loadings for alcohol and coffee and ii) mixed: rice; bean; flour and pasta; breads; cake and cookies; soda and juice; sugar and sweets; fatty foods; meats; chicken; and eggs. The linear regression showed that the income (β=0.0002; 95%CI: 0.0002-0.0004) and schooling (β=0.0491; 95%CI: 0.0264-0.0718) were positively associated with healthy pattern, and parity (β=-0.1044; 95%CI: -0.1665- -0.0423) and skin color (β=-0.3102; 95%CI: -0.5256- -0.0947) were negatively associated. Skin color (β=0.1647; 95%CI: 0.0378- 0.2916) and marital status (β=0.1065; 95%CI: 0.0062- 0.2067) were positively associated with mixed pattern and income (β=-0.0001; 95%CI:-0.0002- -0.0001) and schooling (β=-0.0281; 95%CI: -0.0417- -0.0146) were negatively associated. CONCLUSION: Socio-demographic factors such as income, schooling, skin color, marital status and parity were associated with dietary patterns in this sample of postpartum women residents in Rio de Janeiro.