Diabetes is the most common metabolic disorder during pregnancy. Its development is related to multiple factors and is associated with maternal and perinatal adverse effects. The objective of this work was to determine the association of nutritional patterns, anthropometric and epidemiological aspects with the diagnosis of Gestational Diabetes Mellitus (GDM) and perinatal outcomes in pregnant women using the Puengasí 2 Health Center and the Isidro Ayora Gynecology-Obstetric Hospital. A prospective cohort study was carried out in 523 pregnant users of the Puengasí 2 Health Center and the Isidro Ayora Gynecology-Obstetric Hospital in the city of Quito from January 2021 to March 2023. The structured, Global Physical Activity Questionnaire (GPAQ), and 24-hour recall questionnaires were administered. Additionally, perinatal medical records were reviewed. Exploratory factor analysis was conducted to identify nutritional patterns. Descriptive analysis of sociodemographic and lifestyle factors was performed. Bivariate and multivariate analyses were used to establish the relationship between affinity for nutritional patterns and sociodemographic and lifestyle factors. The prevalence of GDM was also calculated. Finally, the association between affinity for nutritional patterns, anthropometric and epidemiological aspects, perinatal outcomes, and the diagnosis of GDM was analyzed. Three dietary patterns were identified. The "Dairy, Salads, and Sweet Snacks/Dressings" pattern showed a positive association with foreign nationality. The "Refined Carbohydrates" pattern showed a negative association with education equal to or less than seven years and income up to a basic salary. The "Traditional Ecuadorian" pattern showed a positive association with origin in the coastal region of Ecuador. The prevalence of GDM was 14.3%.Multivariate analysis confirmed the association of GDM with minority ethnicities (Afrodescendant and others), higher body mass index at the beginning of gestation, higher affinity for the Ecuadorian nutritional pattern, greater weight gain during pregnancy, cesarean section, and higher birth weight. No association was found between GDM and lifestyle factors such as physical activity, sedentary behavior, tobacco use or exposure, and alcohol consumption. In conclusion, three nutritional patterns were identified among pregnant women and their association with sociodemographic variables. The prevalence of gestational diabetes mellitus (DMG), currently at 14.3%, is suggested to be underestimated due to the methods used for diagnosis. Minority ethnicities, a preference for the dietary pattern known as "Traditional Ecuadorian," and higher weight gain during pregnancy are associated with an increased risk of DMG. Perinatal outcomes associated with DMG include cesarean delivery and higher birth weight. No association was found between the lifestyle of the pregnant women and the diagnosis of DMG. These findings highlight the importance of considering sociodemographic and nutritional factors in relation to DMG during pregn...