Many have. This label encoumpases a broad range of issues. It can be as simple as inadequate feeds in a normal kid to a medical problem with excessive nutrient loss. The behavioral interplay between caregiver & infant may also facter in. Undernutrition eventually results in increased susceptability to infection and poor respons to rx. In many countries this eventually leads to death. Proper rx can save most.
Yes. Yes, but it would be rare in western developed countries. Failure to thrive is not uniform diagnosis. There are two distinct situations. Child does not get enough food/calories or despite adequate amount of calories due to other diseases child is not growing. Inadequate nutrition may lead to death due to chemical abnormalities and decreased immunity; read about famine in poor countries.