in guideline Neurodevelopmental Abnormality Developmental Delay Sufficient Can have many different causes, such as genetic causes (like Down syndrome), or complications of pregnancy and birth (like prematurity or infections). Often, however, the specific cause is unknown. Some causes can be easily reversed if caught early enough, such as hearing loss from chronic ear infections, or lead poisoning. http://www.med.umich.edu/yourchild/topics/devdel.htm SCDO:0001293 NCIT:C116942 Failure to meet, or late achievement of developmental milestones. Sickle Cell Disease in Children, Standards and Guidelines for Clinic Care Evidence-Based Management of Sickle Cell Disease