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Failure to Thrive

By Elizabeth J. Palumbo, MD, Private Practice, The Pediatric Group, Fairfax, VA

Failure to thrive is a delay in weight gain and physical growth that can lead to delays in development and maturation.

  • Medical disorders and a lack of proper nutrition are causes of failure to thrive.

  • The diagnosis is based on a child's growth chart values, physical examination, health history, and home environment.

  • Children who are undernourished during the first year of life may have developmental delays.

  • Treatment depends on the cause.

During the first year of life, an infant's weight and length are charted at each doctor's visit to make sure that growth is proceeding at a steady rate. Percentiles are a way of comparing infants of the same age and sex. For example, saying that an infant is at the 10th percentile for weight means that of 100 babies of the same age and sex, 90 weigh more and 10 weigh less. Although some infants are smaller and some are larger, infants typically stay at about the same percentile as they grow.

Failure to thrive is a diagnosis given to children who are consistently underweight, typically below the 3rd to 5th percentiles, when compared to children of the same age and sex. Failure to thrive is also considered in infants who have a steady drop in their weight percentile even though their actual weight is not low. For example, doctors would be concerned about an infant who dropped from the 90th percentile to the 50th percentile (average weight) in a short period of time. There are many causes.


Causes of failure to thrive can involve

  • Environmental and social factors

  • Medical disorders

Environmental and social factors are the most common reasons why children do not get the nutrition they need. Whatever the cause, inadequate nutrition can affect the growth of a child’s body and brain.

Poor intake of food may reflect inadequate parenting or environmental stimulation. Parental neglect or abuse, parental mental health disorders, poverty, and chaotic family situations all increase the risk that routine, nutritious meals will not be provided. Such situations also may blunt the child's appetite and decrease the child's intake of food. Sometimes parents provide food with poor nutritional value, which can lead to poor intake and poor weight gain.

Sometimes failure to thrive is caused by a medical disorder in the child. The disorder can be as minor as difficulty chewing or swallowing (as with a cleft lip or cleft palate). Medical disorders, such as gastroesophageal reflux, narrowing of the esophagus, or intestinal malabsorption, may also affect a child's ability to retain, absorb, or process food. Infections, tumors, hormonal or metabolic disorders (such as diabetes or cystic fibrosis), heart disease, kidney disease, genetic disorders, and human immunodeficiency virus (HIV) infection are other physical reasons for failure to thrive.


Doctors diagnose failure to thrive when a child's weight or weight gain is well below what it should be when compared with past measurements or standard height-weight charts (see Weight and Length Charts for Infants from Birth to 24 Months of Age). If failure to thrive affects an infant's weight severely enough, height and head (brain) growth rates are also affected.

To determine why a child may be failing to thrive, doctors ask parents specific questions about feeding; bowel habits; social, emotional, and financial stability of the family, which might affect the child's access to food; and illnesses that the child has had or that run in the family. The doctor examines the child, looking for signs of conditions that could explain the child's poor weight gain. The doctor makes decisions about blood and urine tests and x-rays based on this evaluation. More extensive testing is performed only if the doctor suspects an underlying disease.


Because the first year of life is important for brain development, children who become undernourished during this time may fall permanently behind their peers, even if their physical growth improves. In about half of these children, mental development, especially verbal skills, remains below normal, and these children often have social and emotional problems.


Treatment depends on the cause. If a medical disorder is found, specific treatment is given. Otherwise, treatment depends on how far below normal the child's weight is. Mild to moderate failure to thrive is treated with nutritious, high-calorie feedings given on a regular schedule. Parents may be counseled about family interactions that are damaging to the child and about financial and social resources available to them. Severe failure to thrive is treated in the hospital where social workers, nutritionists, feeding specialists, psychiatrists, and other specialists work together to determine the most likely causes of the child's failure to thrive and the best approach to feeding.