Psychosocial Failure to Thrive Infants or young children who are much smaller than would be expected at a particular age can be a difficult diagnostic problem for physicians. After excluding those infants who are small because they were small at birth, there remains a large group of infants with low weights and perhaps short lengths and small head circumferences. These children may also demonstrate delayed development and abnormal behavior. Some of the small children, however, do have hidden medical problems. Hospitalization may be required to screen for significant medical illness and more important, to see if the child responds to adequate nutrition and a nurturing environment with a rapid weight gain and, more appropriate behavior.
Evaluation consists of more than weighing and measuring the baby.
The behaviors of the child and the parent should be observed, ideally during feeding and the child's response to feeding should be noted.