Slow Weight Gain in Infants and Children

What is slow weight gain?

Slow weight gain is sometimes called “failure to thrive." It is not a disease itself, but a manifestation of many medical, social and environmental factors that prevent a child from getting the calories they need for healthy growth.

Typically, a baby’s weight doubles within their first 4 to 6 months of life and triples in their first year. For instance, a baby born weighing six pounds would typically weigh about 12 pounds by the time they were 6 months old and about 18 pounds by the time they turned 1.

Slow weight gain is not always a concern. Some infants and children are simply smaller than most other children their age. However, between 1 and 10 percent of children in the United States show delays that require some form of intervention. It is important to tell your child’s physician about any delays in your child’s growth.

When is slow weight gain a problem?

Slow weight gain is a problem when it interferes with a child’s healthy development, particularly during your baby’s first year when their brain is developing.

Slow weight gain could be a problem if:

  • your newborn doesn’t regain their birth weight within 10 to 14 days after their birth
  • your baby up to 3 months old gains less than an ounce a day
  • your infant between 3 and 6 months gains less than 0.67 ounces a day
  • your child of any age has been growing steadily and suddenly stops growing

Although you should always discuss slow weight gain with your child’s doctor, it is less of a concern when:

  • your newborn wakes up on their own and wants to feed 8 to 12 times a day
  • your baby is growing at a steady rate
  • your baby has about the same number of wet and dirty diapers as other babies

How we care for slow weight gain

The Growth and Nutrition Program at Boston Children's Hospital is a multidisciplinary program of doctors, nurses, dietitians, social workers, behavioral specialists and speech therapists who will work together to determine the causes and treatment for slow weight gain for your child. We work in partnership with parents, primary care providers, and staff from other disciplines across the hospital to develop an individual long-term treatment plan for each child and address the factors affecting their growth.

If your child’s gain in height is the primary concern, not their weight gain, we may refer your child to the specialists in Department of Endocrinology.