Failure to thrive (FTT) refers to a phenomenon in which children weigh less than what is expected for their age and gender. This term does not include children with genetic short stature, former premature infants, or infants with intrauterine growth restriction who have an appropriate weight-for-length ratio and normal growth velocity. This entry describes a wide variety of medical problems and psychosocial stressors that contribute to FTT. This entry also describes effects that FTT has on long-term development, and management and prevention of potential damage to the brain.

There is no unifying consensus on the definition of the term failure to thrive. However, in medical literature the term typically refers to a phenomenon in which a child has a weight (or weight for height) that is ...