Purpose To compare the introduction of consistencies during the period of complementary feeding of preterm and full-term newborns up to 12 months of life, as well as to evaluate the presence of oral motor dysfunction and its relation to difficulty in introducing food consistencies in these groups. Methods This is an observational, analytical, cohort study, with ambispective data collection, carried out at the Municipal Department of Health of Mafra, state of Santa Catarina, Brazil. The study sample consisted of 87 newborns, 41 full-term and 46 preterm. While data was collected, interviews were held with the mothers/guardians. The anthropometric assessment was carried out by a nutritionist by measuring body weight, length, and head circumference, followed by assessment of oral and functional motor skills by the adapted Clinical Evaluation Protocol of Pediatric Dysphagia (PAD-PED), assessment of breastfeeding and neuropsychomotor development, and assessment of the presence of maternal depression and psychological risk of children with up to 12 months of corrected age. Results We verified oral motor dysfunction in 15 newborns, in both groups, in the liquid consistency in the first assessment, persisting in two cases in the full-term newborns and in three cases in the preterm infants, in the last assessment for the solid consistency. Conclusion We observed no difference in the introduction of food consistencies between groups. Breastfeeding was more frequent in newborns in the first assessment and similar in other assessments. Regarding the predictors for oral motor dysfunction, bottle feeding increased the odds by about seven times and invasive oral procedures by about six times.