Poor weight gain in infants and children

POOR WEIGHT GAIN OVERVIEW

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 or failure to thrive.

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.

HOW IS POOR WEIGHT GAIN DEFINED?

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. In the United States, standard growth charts are published by the Centers for Disease Control and Prevention (CDC); these charts are available for boys and girls and are appropriate for all races and nationalities.

For children two years and older, charts are available here for boys (figure 1) and here for girls (figure 2). For children less than two years old, charts are available here for boys (figure 3) and here for girls (figure 4).

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 CAUSES

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 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 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)
• Neonatal (<1 month) – 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
• Three to six months – Underfeeding (sometimes associated with poverty or not understanding dietary needs of infants); improper formula preparation; milk protein intolerance; problems with child's mouth/throat; medical problems that affect absorption of nutrients (celiac disease; cystic fibrosis); medical problems that increase the number of calories needed (congenital heart disease), gastroesophageal reflux
• Seven to 12 months – Feeding problems (eg, struggles between the child and parent about what will be eaten; problems with the child's mouth that make it hard to adapt to textured foods, not introducing solids by six months of age; refusal to eat new foods when first offered, and then not offering the food again); intestinal parasites
• Over 12 months – Easily distracted at meal time; illness; new stress at home (divorce, job loss, new sibling, death in the family, etc); social issues (underfeeding related to fear of overfeeding, limiting food choices, poverty); sensory-based feeding disorders in children with developmental disorders (eg, autism); swallowing dysfunction  

POOR WEIGHT GAIN DIAGNOSIS

If an infant or child slows or stops gaining weight, it is important to try to determine and treat the underlying cause. The first step is a complete medical history and physical examination. Most children will not require blood testing or imaging tests, although testing may be recommended in certain situations.

The parent(s) should mention if the child has any of the following:

• Vomiting, diarrhea, or rumination (swallowing, regurgitating, then re-swallowing food).
• Avoids foods with particular textures (eg, hard or crunchy), which may be a sign of a problem with chewing/swallowing.
• Avoids types or groups of food (eg, milk, wheat), which can be a sign of a food allergy or intolerance.
• Drinks large amounts of low-calorie liquids or fruit juices. Drinking these beverages may prevent the child from eating solid foods, which contain more calories.
• Follows a restricted diet (vegetarian, wheat or lactose free, etc).
• Behavioral rigidity or sensory aversions that result in self-imposed feeding restrictions.
• Parents should also mention if they have eliminated foods from the child's diet due to concern about the effects of these foods (eg, abdominal pain, diarrhea, "hyperactivity").

The provider may also ask about the child's household, including who lives in the child's house, if there have been recent changes or stresses (eg, divorce, illness, death, new sibling), or if anyone in the house has a medical or psychiatric illness, including history of feeding/eating disorder. The provider may also ask about the food supply (eg, if there have been days when anyone in the family went hungry because there was not enough money for food). Although these questions can be difficult to answer, it is important to be honest.

In some cases, the provider will ask the parent(s) to keep a record of everything the child eats and drinks for a few days (form 1). This can help to determine if the child is eating an adequate number and type of calories.