When and How to Start Prophylaxis in Children with Hemophilia.

Background: Hemophilia A and B are X-linked inherited bleeding disorders resulting from factor VIII or IX deficiency and are associated with substantial morbidity beginning in early childhood. Recurrent musculoskeletal bleeding can lead to hemophilic arthropathy and long-term disability. Intracranial hemorrhage, especially in early infancy, remains a life-threatening complication with high risks of mortality and neurological sequelae. As treatment decisions in early life decisively influence lifetime outcomes, the optimal timing and mode of prophylaxis are central aspects of pediatric hemophilia care. Summary: This review summarizes the current evidence and expert opinions regarding the initiation of prophylaxis in children with hemophilia, focusing on early diagnosis, perinatal management, the timing of and indications for prophylaxis, therapeutic options, inhibitor development, and psychosocial aspects. Prophylaxis is recommended as early as possible in children with severe hemophilia and in those with moderate disease and a severe bleeding phenotype, ideally before the first joint bleed, to prevent future bleeds and microbleeds and to therefore preserve joint health. The choice of therapy (nonfactor replacement therapy, factor concentrate) should be individualized on the basis of the type and severity of hemophilia, patient age, venous access, risk of inhibitor development, clinical presentation, and family circumstances. For hemophilia A, the early use of nonfactor therapy (emicizumab) in newborns and toddlers represents an efficacious and safe therapeutic option. Data on FVIII inhibitor development in children on nonfactor prophylaxis with infrequent exposure to FVIII are still lacking. In the course of life with improved venous access, switching to FVIII prophylaxis may be beneficial in cases of bleeding despite prophylaxis with nonfactor therapy in daily life or based on parental choice. The psychosocial impact on patients and their families, especially related to treatment burden and venous access, highlights the need for shared decision-making and multidisciplinary care. Key Message: Early individualized prophylaxis is the cornerstone of modern pediatric hemophilia management. For children with hemophilia, prompt initiation after diagnosis, tailored therapeutic approaches, and close interdisciplinary support are essential for preventing life-threatening bleeding, preserving musculoskeletal and neurodevelopmental health, and ensuring a normal quality of life and participation in daily activities.