Aims: The link between deformational plagiocephaly and psychomotor development is a recurrent question in medical publications. Main publications concentrate on term infants, but there is a lack of data on the impact of deformational plagiocephaly on the long-term neurodevelopment of premature infants. We attempted to establish a possible relation between deformational plagiocephaly during the 1st year of life and the psychomotor score at 4 years in prematurely born infants. Other risk factors potentially impacting the psychomotor score were also studied. Material and methods: A retrospective study of the files of the children followed by the "Naître et Devenir Région PACA Ouest Corse Sud" healthcare network and included in the database allowed us to select a cohort of 594 infants born prematurely at under 33 weeks of gestational age. These children were developmentally evaluated during the 1st year of life and at 4 years or age using the "EVAL Mater" test. The "Naître et Devenir" network is following up infants born prematurely at under 33 weeks of gestation in the West Provence Alpes Côte d'Azur and South Corsica region, from discharge to 7 years. A group of 170 specially trained pediatricians follow these infants developmentally at term, 3, 6, 9, 12, 18, and 24 months of corrected age and 3, 4 5, 6, and 7 years. Data are collected in a specially designed database. Results: There was no significant link between deformational plagiocephaly during the 1st year of life and a pathological psychomotor score at age 4, but some risk factors were demonstrated: male gender, birth at under 28 weeks of gestational age, weight at birth under 1000g, having a Latal and Ferriero neuromotor score equal to or greater than 2 at 3 months of corrected age, and to a lesser extent having a prescription for physiotherapy during the 1st year. Conclusion: The research on deformational plagiocephaly in the full-term infant suggests a relation between deformational plagiocephaly and developmental delay predominantly on the motor side, with an increased rate of special needs services at school age. The question is raised of whether deformational plagiocephaly is the cause of the delay or an early sign of cerebral anomaly with an early motor delay in full-term infants. The results suggest that deformational plagiocephaly in the prematurely born infant may not be related to neurodevelopmental delay but simply to the extended time spent in the supine position because of the early birth associated with physiological hypotonia and axial extension. Other risk factors such as male gender, birth before 28 weeks of gestation, weight less than 1000g, a Latal and Ferriero neuromotor score greater than 2 at 3 months of corrected age, and having a prescription for physiotherapy during the 1st year of life are strongly related to delayed psychomotor development at age 4.