What you need to know about failure to thrive

Riley* was a textbook healthy baby. He was content and easygoing, and throughout most of his first year, was trending between the 90th and 95th percentiles for growth. But his mom, Kate Lefler*, knew something wasn’t right. Because she was having trouble with breastfeeding, she switched Riley to formula at four months. He became fussy, suffered from constipation and vomiting, and developed severe eczema. She changed brands several times to no avail, and as he got older she started him on solid foods, but by the time his 12-month checkup rolled around, he hadn’t grown in three months. His parents were told he had failure to thrive (FTT).

Failure to thrive usually affects kids two and under, and is used to describe those who are considerably small for their age. To determine if a baby has FTT, doctors measure and track her weight, height and head circumference on a growth chart at regular checkups. There is cause for concern if the baby’s weight is below the third percentile for his age and gender, if there’s a decrease in the rate of weight gain or if the child’s weight is low in comparison to his height. Riley’s doctor was worried that his growth had come to such a sudden stop.

“Failure to thrive is not a diagnosis—it’s a symptom,” says Julie Johnstone, a paediatrician with the failure to thrive group at the Paediatric Consultation Clinic at the Hospital for Sick Children. “If we find that somebody has FTT, then we need to figure out why.” The process starts with a detailed medical history and a physical exam. Depending on what other symptoms are present, blood work, X-ray scans and developmental screenings might be needed too.

Most babies with FTT fall roughly into one of three groups (though there is sometimes crossover between them). The first group isn’t getting enough to eat due to feeding issues, like severe reflux disease, aversions to certain foods, anxiety or, in extreme cases, abuse. In the second group, babies eat enough but have an underlying disease that results in a need for increased calories, like a metabolic or cardiac issue. The third group eats but the babies don’t absorb the calories and nutrients, which can happen because of gastrointestinal issues or endocrine abnormalities.

If there’s an underlying medical reason for FTT, the first priority is to treat that condition. A team of experts, including the paediatrician or family physician, a dietitian, a social worker, a nurse and any specialists who may be involved, develops a management plan specific to each baby’s needs. He may also be seen by an infant psychiatry team, occupational therapists and speech and language therapists (who, because of their expertise with the physiology of little mouths, also work on feeding problems).

The next issue is the patient’s ongoing nutritional needs. Those two and under, who are at the highest risk for FTT, are also in a critical period of development. “Underlying malnutrition can lead to long-term developmental implications, so the sooner it can be addressed, the better chance we have,” says Johnstone. Babies might be given fortified formula or receive a formula supplement if they’re nursing.

As for Riley, while doctors never uncovered the reason for the initial stall in his growth, testing at 15 months revealed that food allergies were the culprits in his ongoing failure to thrive. Within a week of eliminating the allergens, the happy kid that Lefler knew was back. “His face started clearing up, he started sleeping, and he was happier,” she says. And now Riley, who has just turned two, is right back up in the 95th percentile.

* names have been changed

Try this: To help older kids who aren’t gaining weight quickly enough, incorporate lots of nutritious foods that are high in calories but still healthy. For example, if you’ve got a pasta lover, add oil or butter; offer full-fat cheeses or hummus as a dip with vegetables; and provide snacks like avocados, natural nut butters and high-fat yogurt. Avoid foods that fill kids up without providing any proper nutrition, such as juice, crackers and rice puffs.

A version of this article appeared in our April 2016 issue with the headline "Failure to thrive", p. 46. 

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