Slow Weight Gain in Infants and Children Symptoms & Causes

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Contact the Growth and Nutrition Program

We understand that you may have a lot of questions when your child is diagnosed with slow or delayed weight gain.
  • How do you define it?
  • What could be contributing to my child’s slow weight gain?
  • What are the recommended courses of action?
  • What are the potential consequences of delays in weight gain?

We’ve tried to provide some answers to those questions here.  When you and your child meet with our experts, they will explain your child’s condition and the recommended options more fully.

What defines normal weight gain?

Growth Curve Genetic

A growth curve for a child whose growth followed one pattern for the first four months of life and then shifted to a new pattern. This pattern can be completely normal, though parents should discuss any changes in their child's rate of growth with their physician.


growth curve undernourished

A growth curve for a child who is undernourished.

A child’s weight and height generally track in a fairly consistent fashion over time, albeit with some fluctuation. This pattern can be described as a percentile on a growth curve. By plotting a child’s weight or height (length in the case of an infant or toddler) over time, a growth curve demonstrates their pattern of growth. Health care providers generally use one of two sets of growth curves to monitor a child’s growth. The World Health Organization (WHO) curve is recommended for children less than two years of age. The U.S. Centers for Disease Control and Prevention (CDC) curve is recommended for children over the age of two. The growth of children with certain known conditions (e.g., a genetic syndrome such as Down syndrome) is best monitored using growth curves developed specifically for those conditions.

Children generally gain weight in proportion to their age and height or length. What is more important than a child’s position on a growth curve (e.g., 25th percentile, 50th percentile, 90th percentile) is his or her pattern of growth. So for instance, a two-year-old boy whose weight has consistently been and continues to be at the 15th percentile for his age is displaying a normal pattern of weight gain.

Sometimes, normal children may grow at a given rate for a certain period of time, followed by a somewhat different rate of growth for another period of time. For example, a two-year-old girl may chart a weight at the 25th percentile for the first year of life, then at the 15th percentile for the second year of life; if there are no worrisome factors, this could be considered a normal pattern of weight gain. Your physician should evaluate any change in your child’s pattern of weight gain to determine whether it falls within the range of normal.

Causes

What could cause a child to gain weight slowly?

There is a range of possible reasons for why a child might gain weight slowly, and often more than one reason is contributing at a time. Any factors that affect a child’s access to food – be they medical, social, economic, etc. – can affect weight gain. Medically, anything that causes the following could be a contributing factor:

  • Inadequate food intake
  • Problems with digestion or absorption of food or absorption
  • Increased metabolism

Children born prematurely (before their due date) are at particularly high risk for delays in weight gain. Also, for some children – those with small parents, for instance – relatively slow weight gain may be normal.

Parents should always discuss a slow rate of weight gain with their physician.

Signs and symptoms

What defines slow weight gain?

As noted above, health care providers expect to see a child maintain a stable pattern of growth – that is, growth that consistently follows a particular weight-for-age or weight-for-height percentile. If the pattern changes significantly, concerns can arise.

A child’s weight gain raises concern when:

1.     Their weight or weight-for-height is two or more standard deviations below the mean for their gender and age; or

2.     Their weight curve has crossed downward by more than two major percentile lines on the CDC or WHO growth curves after having previously achieved a stable pattern of growth.

As noted above, some healthy children may achieve a stable pattern of growth and have their growth slow such that they continue on another curve. Any change in pattern should be discussed with your child’s physician.

How is slow weight gain diagnosed?

Medical history family history, and physical examination are critical in finding the reason(s) for your child’s slow weight gain. Carefully chosen laboratory tests and other diagnostic studies can also provide valuable information.

For details, see Tests.

What can be done in cases of slow weight gain?

We work with your family and your child’s primary care provider to develop a comprehensive, long-term plan aimed at improving your child’s weight gain.

For details, see Treatment & Care.

How can slow weight gain affect my child in the long term?

The outlook for a child with slow weight gain depends on the timing and severity of the issue, as well as on the presence of any underlying disease. In addition, your child’s genetic potential for growth can also have an effect.

Questions to ask your doctor

You and your family play an essential role in addressing your child’s growth. It’s important that you share your observations and ideas with your child’s treating providers, and that you have all the information you need to fully understand the treatment team’s explanations and recommendations.

You may have many questions about your child’s growth. It’s often very helpful to jot down your thoughts and questions ahead of time and bring them with you, along with a notebook, to your child’s appointment. That way, you’ll have all of your questions in front of you when you meet with your child’s treating providers and can make notes to take home with you.

Some questions to ask your doctor might include:

  • What is causing my child's slow weight gain and how was this diagnosis arrived at?
  • Are there any other conditions my child might have instead?
  • Does my child need further testing?
  • What is the long-term outlook for my child?
  • Are there medications that will be prescribed and do they have potential side effects?
  • How should I talk to my child and other concerned family members about this condition and the potential impact upon his or her long-term health?
  • Do I need to make any changes to my child’s home and school routines?
  • Can you point me to educational and support service resources for children with slow weight gain in my area?
  • What other resources can you direct me to for more information, as well as for additional evaluations and interventions?
We are grateful to have been ranked #1 on U.S. News & World Report's list of the best children's hospitals in the nation for the third year in a row, an honor we could not have achieved without the patients and families who inspire us to do our very best for them. Thanks to you, Boston Children's is a place where we can write the greatest children's stories ever told.”
- Sandra L. Fenwick, President and CEO

Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115 617-355-6000 | 800-355-7944

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