Question: Ohio Subscriber Answer: Code 783.40 (Lack of normal physiological development, unspecified) is more appropriate for "gross motor delay," which is a developmental delay. This notation should be sufficient documentation to use 783.40. Other terms that fall under 783.40 include "inadequate development" and "lack of development." Here's the inside scoop on the codes you mention: • Category 315 (Specific delays in development), which includes 315.9 (Unspecified delay in development) refers more to central nervous system (CNS) delays, such as speech (315.39, Developmental speech or language disorder; other) and ataxia (315.31, Expressive language disorder) than physiologic delays. Tip: * A physiologic delay refers to abnormal internal functioning of the body. * Gross motor physiologic delay means abnormal movement of a person's large body muscles including legs, arms, and abdomen, which inhibit normal walking, jumping and running.