Maternal obesity is one of the main public health problems ata world level. It is a multifactorial disease with multiplecauses, and few studies exist on its dietary patterns, physicalactivity and social determinants. This work aims to identifydeterminants of maternal obesity in a middle income coun-try. Research is based on a prospective cohort design. Datawere collected using questionnaires applied to pregnantwomen. Three dietary patterns were identified, and only halfof the women carry out physical activity. The regressionanalysis showed an association between overweight/obesityand the following variables: age 25 to 29 years old (3.8; CI1.6‐9.0), 30 to 34 years old (3.7; CI 1.2‐11.6); health prob-lems during pregnancy (2.1; CI 1.0‐4.1); socio‐economicincome (1.73; CI 1.54‐2.05); hypertension (2.7; CI 1.4‐4.5);mild food insecurity (1.9; CI 1.0‐3.8); moderate insecurity(3.7; CI 0.92‐15.4); refined food dietary pattern (.76;CI.61‐.95). The risk of increasing BMI during pregnancymainly depends on socioeconomic and demographicvariables such as age, educational level, income, food insecu-rity, and dietary pattern. This study's results could be used asevidences for the revision, planning, and adjustment of inter-ventions for the prevention and management of maternalobesity, as a part of the national strategies againstoverweight and obesity.