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How Does Cystic Fibrosis Affect Growth and Development in Children?

Trouble growing and gaining weight is one of the most common problems children with CF face. Growing requires extra energy and nutrients in any child, but children with CF need extra calories (energy) to breathe and fight infections. Thus, trouble gaining and keeping on weight is a sign that the gastrointestinal system is not absorbing the nutrients a child needs to grow.

BMI goals for infants and children with cystic fibrosis

It is recommended that babies and preschoolers with CF should weigh at or above the 50th percentile for their height/length, which may look slightly chubby. A higher BMI helps a young child grow properly and is linked to better lung function later in life. Those between ages 2 and 20 should aim for a BMI at or above the 50th percentile for their height and weight.1-3

Causes of poor growth in children with cystic fibrosis

GI problems tend to occur in children with CF because the thick mucus clogs the ducts (tubes) leading in and out of the pancreas, liver, and intestines. It also may slow the movements that help food progress through the GI system. These blockages prevent sufficient amounts of digestive enzymes from mixing with the food. Without the enzymes, nutrients in the food cannot be absorbed by the body. Belly pain, nausea, vomiting, and acid reflux are also common.

Adding to this, children with CF tend to burn more calories due to the extra work it takes to breathe and fight infections. In fact, people with CF need up to twice the daily recommended calories, on top of what is needed for normal childhood growth. All this leads to malnutrition and trouble gaining enough weight to grow.2

Problematic GI symptoms

Other common GI symptoms that may contribute to a child not wanting to eat, making it difficult for a child with CF to get enough calories and nutrients:

Treatment for poor growth

Doctors treat failure to growth aggressively because research shows that maintaining a healthy weight helps reduce exacerbations and lung infections and improves quality of life. When a child with CF does contract an infection, carrying enough weight helps them fight the infection.2

Pancreatic enzyme replacements

First, doctors prescribe pancreatic enzyme replacements, which help the child with CF break down (digest) their food and get enough energy and nutrition from the foods they eat. Kids with CF are also usually encouraged to eat as much as they’d like of high-calorie, high-fat foods, along with fruits and vegetables. A diet with 40 percent of total calories from fat is generally recommended. More frequent, small, high-calorie meals may be necessary to help a child with CF get enough to eat.1-3

Taking supplements and tube feeding

Vitamin supplements may also be prescribed to help the child get the nutrients they need. Some children may need to have an enteral feeding tube (feeding tube or g-tube) inserted so that overnight feedings can be given to boost their nutritional intake.2

Working with a dietician

A dietitian with a specialty in CF will have tips and ideas that help a family make sure their child gets enough nutritionally-dense calories without developing eating fatigue.

Written by: Jessica Johns Pool | Last reviewed: September 2019
  1. Elborn JS. Cystic fibrosis. Lancet 2016; 388:2519-31. http://dx.doi.org/10.1016/S0140-6736(16)00576-6.
  2. Dennett C. MNT in Cystic Fibrosis Care — What RDs Need to Know. Today's Dietitian. April 2017. Vol. 19, No. 4, p. 44.
  3. Cystic Fibrosis Foundation. Nutritional Basics. Available at: https://www.cff.org/Life-With-CF/Daily-Life/Fitness-and-Nutrition/Nutrition/Getting-Your-Nutrients/Nutritional-Basics. Accessed 5/22/2019.