Failure to thrive refers to a child's inability to gain weight and grow as expected. Most diagnoses of failure to thrive are made in the first few years of life. More to Know Failure to thrive can be caused by a variety of medical conditions and social factors ranging from gastrointestinal problems and metabolic disorders to poor nutrition and emotional deprivation. Infants or children who fail to thrive do not follow standard growth charts for height, weight, and head circumference. In addition, their weight is lower than the 3rd percentile and 20% below the ideal weight for their height. Their personal growth curve may slow down or stop altogether. Undernourished kids can become constipated, disinterested in their surroundings, irritable, and lethargic. They might not reach developmental milestones like sitting up, walking, and talking at the usual age. Teenagers might not see the changes that puberty usually brings. Failure to thrive is treated according to the cause. The primary goal of treatment is usually to increase the number and quality of calories consumed. Keep in Mind When diagnosed and treated early, infants and children who are failing to thrive can begin or continue to grow and develop normally. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Failure to Thrive Most kids grow well but some have ”failure to thrive.” This means they don't gain weight as expected and may not grow as tall as they should. Read More What Is a Growth Disorder? The other kids in the class have been getting taller and developing into young adults, but your child's growth seems to be lagging behind. Could a growth disorder be the cause? Read More Growth Charts Doctors use growth charts to figure out whether kids' height and weight measurements are "normal" and whether they're developing on track. Here are some facts about growth charts. Read More Your Child's Growth From the moment parents greet their newborn, they watch the baby's progress eagerly. But how can they tell if their child is growing properly? Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.