Patient education: Poor weight gain in infants and children (Beyond the Basics)



During infancy and childhood, children gain weight and grow more rapidly than at any other time in life. However, some children do not gain weight at a normal rate, either because of expected variations related to genes, being born prematurely, or because of undernutrition, which may occur for a variety of reasons. Undernutrition is sometimes called a growth deficit, weight faltering, or faltering growth.

It is important to recognize and treat children who are not gaining weight normally because it may be a sign of undernutrition or an underlying medical problem that requires treatment. Undernutrition can have complications, such as a weakened immune system, slower than expected linear growth, shorter than expected height, or difficulties with learning. These complications are more common in children who are undernourished for a long period of time.


Poor weight gain is defined as gaining weight at a slower rate than other children who are the same age and sex. “Normal” ranges for weight are based upon the weight of thousands of children. Standard growth charts are published by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO); these charts are available for boys and girls and are appropriate for all races and nationalities.

For children less than two years old, the WHO growth standards are used. Charts are available here for boys (figure 1) and here for girls (figure 2). For children two years and older, the CDC growth charts are used. They are available here for boys (figure 3) and here for girls (figure 4). Children with particular genetic syndromes may require special growth charts. As an example, a growth chart for children with Down syndrome is available from the CDC.

Weight gain normally follows a predictable course from infancy through adolescence. However, some children do not gain weight normally from birth, while other children gain weight normally for a while, then slow or stop gaining weight. Weight gain usually slows before the child slows or stops growing in length.

A child is said to have poor weight gain if he or she does not grow at the expected rate for their age and sex.


Poor weight gain is not a disease, but rather a symptom, which has many possible causes. The causes of poor weight gain include the following:

Not consuming an adequate amount of dietary energy (measured in calories) or not consuming the right combination of protein, fat, and carbohydrates

Not absorbing an adequate amount of nutrients

Requiring a higher than normal amount of dietary energy (measured in calories)

Poor weight gain can occur as a result of a medical problem, a developmental or behavioral problem, lack of adequate food, a social problem at home, or most frequently, a combination of these problems. Common causes of poor weight gain for each age group are described below:

Prenatal – Small for age at birth (called intrauterine growth restriction); prematurity; prenatal infection; birth defects; exposure to medications/toxins that limit growth during pregnancy (eg, anticonvulsants, alcohol, tobacco smoke, caffeine, street drugs)

Birth to six months – Poor quality of suck (whether breast- or bottle-fed); incorrect formula preparation; breastfeeding problems; inadequate number of feedings; poor feeding interactions (eg, infant gags or vomits during feedings and parent assumes child is full); neglect; birth defects that affect the child’s ability to eat or digest normally; underfeeding (sometimes associated with poverty or not understanding dietary needs of infants); milk protein intolerance; problems with child’s mouth/throat that make it difficult for the child to suck or swallow (eg, cleft lip and palate); medical problems that affect absorption of nutrients (cystic fibrosis); medical problems that increase the number of calories needed (congenital heart disease), gastroesophageal reflux .

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