Children come in different sizes and shapes. Although your child may be taller or shorter, or heavier or lighter than other children of the same age, changes in height and weight generally follow a regular pattern that is right for your child.

Babies grow at different rates. For example, breastfed babies tend to grow more quickly than nonbreastfed babies in the first six months of life, and tend to grow more slowly in the second six months of life. Nonbreastfed babies tend to grow faster in the second six months of life.

The way your child grows says a lot about her health. Growing too fast or too slowly can be a sign of possible problems with health or nutrition.

Starting from birth, your child’s weight and length/height should be measured on a regular basis to see how he is growing over time. Babies and toddlers should also have the size of their head measured (head circumference).

Your child should be weighed and measured at all regularly scheduled well-child visits and/or at visits when your child is ill. Typical well-child visits may occur:

• within 1 to 2 weeks of birth,

• at 2, 4, 6, 9, 12, 18 and 24 months, and

• once per year for children older than 2 years of age and for adolescents.

At a glance

Taking accurate height and weight measurements is essential for correct body mass index (BMI) and BMI percentile calculations. Follow these steps when measuring children's height and weight.

How to measure height accurately

Follow these steps to measure a child's height accurately.

1. Remove the child's shoes, bulky clothing, hats, and hair ornaments. Undo hairstyles that interfere with getting an accurate height measurement.
2. Have the child stand:
   1. On firm flooring, such as tile or wood rather than carpet.
   2. Against a flat surface, such as a wall with no molding.
   3. With their feet flat, together, and against the wall.
   4. With legs straight, arms at their sides, and shoulders level.
3. Make sure the child is looking straight ahead.
4. Measure while the child stands with their head, shoulders, buttocks, and heels touching the flat surface, usually a wall. Depending on the child's body shape, all points may not touch the wall.
5. Use a flat and rigid ruler or book to form a right angle with the wall.
6. Lower the ruler or book until it firmly touches the crown (very top) of the child's head.
7. Make sure the eyes of the person measuring are at the same level as the ruler or book.
8. Lightly mark where the bottom of the ruler or book meets the wall.
9. Measure the distance between the base on the floor and the mark on the wall using a metal tape measure.
10. Accurately record the height to the nearest 1/8^th inch or 0.1 centimeter (for example, 35.2 inches).

How to measure weight accurately

Follow these steps to measure a child's weight accurately.

1. Use a digital scale. Avoid using spring-loaded bathroom scales.
2. Place the scale on firm flooring (such as tile or wood) rather than on carpet.
3. Have the child remove shoes and heavy clothing, such as sweaters.
4. Have the child stand with both feet in the center of the scale.
5. Record the weight to the nearest decimal fraction (for example, 55.5 pounds or 25.1 kilograms).

How to calculate BMI

To calculate BMI by hand, use the formulas below:

• Metric Units: weight (kg) / [height (m)]²
• Metric Units: [weight (kg) / height (cm) / height (cm)] x 10,000
• U.S. Customary Units: weight (pounds) / [height (in)]² x 703

A growth chart is a type of graph used to track your child’s growth pattern. Each time your child is measured, the new weight and length/height measurements are marked on the growth chart.

The chart helps to show whether your child is growing in a healthy way. Your child’s growth chart is kept as part of her health record until she becomes an adult. You can ask to see this growth chart at each visit.

What is a percentile?

Percentiles are the most commonly used clinical indicator to assess the size and growth patterns of individual children in the United States. Percentiles rank the position of an individual by indicating what percent of the reference population the individual would equal or exceed. For example, on the weight-for-age growth charts, a 5-year-old girl whose weight is at the 25th percentile, weighs the same or more than 25 percent of the reference population of 5-year-old girls, and weighs less than 75 percent of the 5-year-old girls in the reference population.

What is a z-score?

A z-score is the deviation of the value for an individual from the mean value of the reference population divided by the standard deviation for the reference population. Because z-scores have a direct relationship with percentiles, a conversion can occur in either direction using a standard normal distribution table. Therefore, for every z-score there is a corresponding percentile and vice versa.

My child is at the 5th percentile on a chart, what should I do?

If you are concerned about your child’s growth, talk with your child’s health care provider.

Which growth charts are appropriate to use with exclusively breastfed babies?

In the United States, the WHO growth standard charts are recommended to use with both breastfed and formula fed infants and children from birth to 2 years of age (CDC, 2010). The WHO growth charts reflect growth patterns among children who were predominantly breastfed for at least 4 months and still breastfeeding at 12 months. These charts describe the growth of healthy children living in well-supported environments in sites in six countries throughout the world including the United States. The WHO growth charts show how infants and children should grow rather than simply how they do grow in a certain time and place and are therefore recommended for all infants (Dewey, 2004; WHO Multicentre Growth Reference Study Group, 2006).

The WHO growth charts establish the growth of the breastfed infant as the norm for growth. Healthy breastfed infants typically put on weight more slowly than formula fed infants in the first year of life (Dewey, 1998). Formula fed infants gain weight more rapidly after about 3 months of age. Differences in weight patterns continue even after complementary foods are introduced (Dewey, 1998).

Why haven’t the 2000 CDC growth charts been updated to reflect today’s US children and adolescents?

There are no plans to update the growth charts.

The 2000 CDC growth charts were created using a reference population from national surveys from 1963 to 1980 for most children and adolescents – before the increase in obesity prevalence. They serve as a “ruler” to compare children today with a historical reference. Because of the increase in average childhood BMI over time, updating the charts with newer data would result in a shift in the percentiles. Specifically, the 95th percentile, the cut point for obesity, would shift upward. Using a new 95th percentile to define obesity would lead to some children being below the 95th percentile who were above using the 2000 charts. As an example, during 2017-March 2020, 19.7% of US children and adolescents were above the 95th percentile of the 2000 CDC BMI-for-age growth charts and had obesity. If the charts were updated to include only these children, 5%, not 19.7%, would be above the 95th percentile. This would lead to two problems for surveillance of child growth and obesity. First, this new 5% of children would have much higher BMI values than the 5% of children in the original 2000 growth chart reference population who were over the 95th percentile. The health implications of these higher BMI values would require new research and definitions. Second, no meaningful point of reference would be available if the growth charts were continuously updated to change the location of the 95th percentile according to the most recent data. For example, the increases in obesity over the past few decades would not have been identified if the point of reference was changed from the original reference data.

Why use WHO growth standards for infants and children ages 0 to 2 years of age in the U.S?

The WHO standards establish growth of the breastfed infant as the norm for growth. Breastfeeding is the recommended standard for infant feeding. The WHO charts reflect growth patterns among children who were predominantly breastfed for at least 4 months and still breastfeeding at 12 months.

The WHO standards provide a better description of physiological growth in infancy. Clinicians often use the CDC growth charts as standards on how young children should grow. However the CDC growth charts are references; they identify how typical children in the US did grow during a specific time period. Typical growth patterns may not be ideal growth patterns. The WHO growth charts are standards; they identify how children should grow when provided optimal conditions.

The WHO standards are based on a high-quality study designed explicitly for creating growth charts. The WHO standards were constructed using longitudinal length and weight data measured at frequent intervals. For the CDC growth charts, weight data were not available between birth and 3 months of age and the sample sizes were small for sex and age groups during the first 6 months of age.

Why use CDC growth charts for children 2 years and older in the U.S.?

The CDC growth charts can be used continuously from ages 2-19. In contrast the WHO growth charts only provide information on children up to 5 years of age.

For children 2-5 years, the methods used to create the CDC growth charts and the WHO growth charts are similar.

In 2006, the World Health Organization (WHO) released new child growth standards. The WHO growth charts are the best tool for tracking a child’s growth. They should replace other growth charts that have been used for healthy term infants, children and teenagers. The WHO growth charts are being used to track children’s growth in many countries all over the world.

The Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) recommend that health care providers in primary care settings use the 2000 CDC growth reference charts for children and teens aged 2 to 20 years to monitor growth in the United States (Grummer-Strawn, Reinold, Krebs, 2010).

The 2000 CDC growth reference charts include the weight-for-age, stature-for-age, and BMI-for-age charts for boys and girls aged 2 to 20 years. This training focuses on using the BMI-for-age growth charts.

What is BMI?

• An anthropometric index of weight and height

Body Mass Index (BMI) is an anthropometric index of weight and height that is defined as body weight in kilograms divided by height in meters squared (Keys et al., 1972).

BMI = weight (kg) / height (m)²

BMI is the commonly accepted index for classifying adiposity in children, teens, and adults.

• A screening tool

BMI is a screening tool used to identify individuals who are underweight, overweight, or obese. BMI is NOT a diagnostic tool (Barlow, 2007).

For example, a child who is relatively heavy may have a high BMI for his or her age. To determine whether the child has excess fat, further assessment is needed. To determine a counseling strategy, assessments of medical risks, behavioral risks, including sedentary time, dietary and physical activity behaviors, and attitudes are needed (Barlow, 2007).

For children and teens, BMI is both sex-specific and age-specific (Barlow, 2007; Hammer et al., 1991; Pietrobelli et al., 1998). Age and sex are taken into consideration for children and teens for two reasons: (1) the amount of body fat differs between girls and boys; and (2) the amount of body fat changes with age.

• An indirect measure of body fatness

BMI is not a direct measure of body fatness. However, BMI parallels changes obtained by direct measures of body fat, such as dual energy X-ray absorptiometry (DEXA). BMI can be considered a proxy for measures of body fat.

Note that the accuracy of BMI as an indicator of body fatness (adiposity) varies depending on the degree of body fatness. In other words, among relatively heavy children, BMI is a good indicator of excess body fatness; however, among relatively thin children (those with a BMI-for-age of 85th percentile), BMI is more an indicator of fat-free mass (Freedman and Sherry, 2009). Fat-free mass is total body mass excluding the fat. Fat-free mass includes everything from your skin, bones, ligaments, and tendons, to your organs and water content.

Many things affect a child’s growth including her eating and physical activity habits, environment and parent’s height. If your child is growing well, his head circumference, weight and length/height will follow (or ‘track’) along the same growth lines over time.

Remember that all children have a pattern of growth that is natural for them. Regular weight and length/height measurements over time will show your child’s special growth pattern.

Talk to your health care provider if you have concerns about your child’s growth.

Children grow and develop at their own rate. It is best to monitor your child’s growth over time rather than compare your child to other children. This can be done by attending all your child’s well-visits with their primary medical provider. Your child’s provider should graph your child’s growth.

A child who plots consistently, even if at the lowest ends of the growth chart, is usually okay if they are gaining weight steadily. However, if a child drops in the growth chart based on height, weight, and age and is no longer gaining weight or gaining at a lower-than-expected rate, it may indicate a problem with growth.

Children are at increased risk for being smaller than expected if:

• There is an underlying medical condition.
• There is poor eating or feeding habits. Children that lack structured mealtimes and/or are forced to eat more than they want often end up eating less.
• They have poor diet quality because either
  • The foods offered to the child lack the nutrients needed to promote adequate growth
  • The child has a poor appetite and is not consuming all the food offered, or
  • There is a lack of food available in the household.

Having adequate nutrition and growth in early life plays an important role in your child’s overall development and their ability to meet their full potential. Inadequate nutrition in early life can lead to several complications, including:

• Short stature and/or stunted growth
• Learning difficulties
• Weakened immune system

The good news is that there are many things you can do to optimize your child’s appetite and promote growth:

• Offer regular meals with sit-down snacks in-between
• Follow the division of responsibility:
  • The parent decides when, where, and what food is served.
  • The child decides how much and if they are going to eat.
• Add additional calories to your child’s diet wherever you can. Ideas include:
  • Add butter or margarine to food
  • Mix in some mashed avocado, or
  • Sprinkle on some extra cheese
• ‘Dress’ your child’s foods with gravies, sauces, dressing, and dips. Never serve food plain.
• When appropriate, involve the child in the planning and preparation of meals and snacks.