A Study to Investigate Bio Product Laboratory Ltd (BPL's) Factor X in the Prophylaxis of Bleeding in Children <12 Years

Inclusion Criteria 1. Children with hereditary severe or moderate FX deficiency (FX:C \<5 IU/dL), based on their lowest reliable FX:C recorded. 2. Children under 12 years old, whose parent/guardian has given informed consent. 3. Children with a history of severe bleeding e.g.: intracranial haemorrhage, before starting prophylactic therapy, OR a mutation in the F10 gene causing a documented severe bleeding phenotype. Exclusion Criteria 1. Children must not suffer from clinically significant liver disease, renal disease, or other coagulopathy or thrombophilia 2. Children must have no history or suspicion of inhibitors to factor X. 3. Children who have known or suspected hypersensitivity to the investigational medicinal product or its excipients. 4. Children with a history of unreliability or non-cooperation. 5. Children who are participating or have taken part in another trial within the last 30 days. 6. Children planning more than 4 weeks' continuous absence from the locality of the investigational site, between the Screening Visit and the End of Study Visit at approximately 6 months (26 weeks) post-Baseline.