Objective: To describe a postnatal series of patients with arthrogryposis multiplex congenita by the causal mechanisms involved. Methods: In this single-center study, the local data warehouse was used to identify patients with arthrogryposis multiplex congenita. Patients were classified into different etiologic groups. Results: Of 82 patients included, the most frequent cause of arthrogryposis multiplex congenita was a neuromuscular disorder (39%), including skeletal muscle (n = 19), neuromuscular junction (n = 3), and peripheral nerve (n = 11) involvement. In other subgroups, 19 patients (23%) were classified by disorders in the central nervous system, 5 (6%) in connective tissue, 7 (8.5%) had mixed mechanisms, and 18 (22%) could not be classified. Contractures topography was not associated with a causal mechanism. Cerebral magnetic resonance imaging (MRI), electroneuromyography, and muscle biopsy were the most conclusive investigations. Metabolic investigations were normal in all the patients tested. Targeted or whole exome sequencing diagnostic rates were 51% and 71%, respectively. Thirty-three percent of patients died (early death occurred in patients with polyhydramnios, prematurity, and ventilatory dependency). Discussion: The benefits of a precise diagnosis in the neonatal period include more tailored management of arthrogryposis multiplex congenita and better genetic information.