Failure-to-thrive is when a child is not growing as expected. It does not include children who are small for their age. Definitions of failure-to-thrive may vary.

Children grow quickly in the first few years of life. A child with failure-to-thrive will usually have a height and weight that is well below other children of their age. Your child may have also had a normal growth pattern that began to slow down. Initially the child has similar height and weight than their peers but at follow-up appointments the child's height and weight does not keep up with their peers.

Growth is assessed at health visits by measuring height, weight, and head circumference. This information is entered into a growth chart, which makes a line or curve that follows how your child grows. Standard curve lines on the chart called percentiles show where babies fall in terms of normal growth compared to other babies at specific ages. Failure-to-thrive can occur when a child:

  • Is at or below the third to fifth percentile for height and weight.
  • Has failed to grow as expected. This is shown by crossing two percentile lines on the growth chart.

Failure-to-thrive is split into three different types. These types include:

  • Organic—caused by some medical condition
  • Nonorganic—occurs in children with no known medical condition
  • Mixed—occurs when the child has features of both

Failure-to-thrive is caused by a lack of nutrition. The most common causes of lack of nutrition include:

  • Inadequate food intake
  • Malabsorption—inability of the intestines to properly absorb nutrients from food
  • Loss of nutrients, which may occur from excessive vomiting or diarrhea
  • Inability to process nutrients correctly
  • Increased energy expenditure