Measurement of growth in children

INTRODUCTION — Measurement of growth enables the clinician to identify normal and abnormal patterns of growth during childhood and adolescence. It is an important component of nutritional assessment. Other components of a complete nutritional evaluation are dietary and medical history, physical examination, and laboratory testing (for selected patients).

Techniques and reference standards for measuring somatic growth are reviewed here. Body composition, which is closely related to somatic growth, is reviewed separately. (See "Measurement of body composition in children".)

Other aspects of the quantitative evaluation of nutritional status are discussed in separate topic reviews:

●(See "Dietary history and recommended dietary intake in children".)

●(See "Malnutrition in children in resource-limited settings: Clinical assessment".)

●(See "Clinical evaluation of the child or adolescent with obesity".)

●(See "Laboratory and radiologic evaluation of nutritional status in children".)

RATIONALE AND GENERAL APPROACH — Growth measurements are the most important components of the nutritional assessment of children because normal growth patterns are the gold standard by which clinicians assess the health and well-being of children. A normal growth pattern does not guarantee overall health; however, children with abnormal growth patterns frequently have nutritional complications of specific clinical disorders (eg, cystic fibrosis, inflammatory bowel disease) or poor socioeconomic conditions. Altered growth patterns are a late consequence of nutritional insult, regardless of the cause of nutritional deprivation. Thus, careful surveillance for nutrition problems, particularly in children who are at risk, is necessary for the prevention of nutritional morbidity. (See "Indications for nutritional assessment in childhood" and "Malnutrition in children in resource-limited settings: Clinical assessment".)

Growth measurements should be plotted on growth charts that provide a reference for the population being measured. Serial measurements must be obtained to determine if the growth pattern is truly abnormal or is a normal variant. However, clinical evaluation with a history and physical examination should not be deferred while awaiting further measurements. Normal variants of growth include constitutional short stature and the gradual movement between growth curves that sometimes occurs in healthy infants and children during the first 24 months of life (sometimes called "rechanneling") (see "Diagnostic approach to children and adolescents with short stature", section on 'Normal growth'). Children whose length, height, or weight measurements fall below the 5^th percentile, above the 95^th percentile, or cross two major centile curves are at nutritional risk and merit further consideration. As an example, if a child's weight falls from the 25^th to the 10^th percentile during one year, the clinician should investigate for an explanation, including signs and symptoms of underlying disease. Growth is most rapid in healthy children during early infancy and adolescence. (See "Normal puberty" and "Normal growth patterns in infants and prepubertal children", section on 'Normal patterns'.)

GROWTH REFERENCES AND STANDARDS

Definitions — Anthropometric measurements are useful only if the clinician is able to correctly interpret them by converting absolute values to relative standards for the appropriate reference population [1]. Growth measurements should be plotted on growth charts that provide a reference for the population being measured. Either a growth reference or growth standard may be used:

●Growth reference – A growth reference refers to a dataset and related growth charts that reflect the population. The Centers for Disease Control and Prevention (CDC) charts are considered a growth reference because they include children raised in a variety of nutritional conditions in the United States.

●Growth standard – A growth standard refers to a dataset and related growth charts that reflect a goal for the population. The World Health Organization (WHO) charts are considered a growth standard because they describe the growth of healthy children under optimal nutritional and environmental conditions.

Commonly used growth charts

Centers for Disease Control and Prevention growth reference — In the United States, the CDC developed growth charts based upon data from five national health examination surveys and five supplementary data sources. Extended growth charts are available to track body mass index (BMI) in children with severe obesity [2].

On these charts, the normal range is generally defined as between the 5^th and 95^th percentiles, although additional categories are also used (eg, defining a category of "overweight" between the 85^th and 95^th percentile).

World Health Organization growth standard — The WHO developed growth standards to describe normal child growth from birth to five years under optimal environmental conditions (WHO Multicentre Growth Reference Study) [3,4]. These standards can be applied to all children everywhere regardless of ethnicity, socioeconomic status, and type of feeding. A pooled sample from six participating countries was used for the development of an international standard of growth. In addition, standardized body mass index (BMI) charts for infants up to five years of age were developed. The reference lines on the WHO growth charts are either percentile lines or Z-scores; Z-scores are units of standard deviation (SD) from the population mean. (See 'Use of Z-scores' below.)

On these WHO charts, the normal range is generally defined as between -2 SD and +2 SD (ie, Z-scores between -2.0 and +2.0), which corresponds to approximately the 2^nd and 98^th percentiles.

Comparison — The WHO standards define a population that is somewhat longer and leaner than the CDC references; this discrepancy is most dramatic during mid- and late infancy [5,6]. When using the appropriate cutoffs (ie, the 5^th and 95^th percentile for the CDC charts and the 2.3^rd and 97.7^th percentiles for the WHO charts), the prevalence of shortness and overweight are similar for both charts (table 1) [6]. However, the prevalence of underweight (low weight-for-age or low weight-for-height) is lower when using the WHO charts compared with the CDC charts. Thus, the main difference is that the WHO standards are less likely to categorize a child as undernourished as compared with the CDC growth references [5,6]. This probably is because the WHO standards were derived from multiple countries, including those that have a lower obesity rate than the United States, whereas the CDC growth references are derived from the United States' population.

Use of Z-scores — Height/length and weight measurements may be converted to Z-scores, which are values that represent the number of SD from the mean value (figure 1). The WHO growth standard uses Z-scores to define the normal range and cutoffs defining abnormal growth, whereas the CDC growth reference uses percentiles. The resulting categories of abnormal growth (underweight/overweight/obesity, short/tall stature) are similar but do not correspond exactly.

As examples:

●Z-score between -2 and +2 – The parameter (eg, height, weight, or BMI) is within 2 SD of the mean for the population. This is considered the normal range; it corresponds to the range between the 2.3^rd and 97^th percentiles.

In some cases, a growth parameter within this normal range may still represent an at-risk group. For example, the WHO defines a BMI Z-score between 1 and 2 as "at risk for overweight" and this category corresponds approximately to the "overweight" category defined by the CDC.

●Z-score <-2 – The parameter is more than 2 SD below the mean for the population; it corresponds to approximately <2.3^rd percentile. As an example, height Z-score <-2 is a common threshold for defining short stature.

●Z-score <-3 – The parameter is more than 3 SD below the mean for the population, corresponding to well below the 1^st percentile.

Most clinicians who use the CDC charts do not use Z-scores routinely, because growth abnormalities can be identified readily by plotting height and weight measurements on the standard growth charts. However, the use of Z-scores is particularly helpful when assessing the growth of a child whose height and weight measurements fall well below or above standard percentile values, when comparing populations that use different standards, or when working with the WHO growth standard, especially in resource-limited settings. (See "Malnutrition in children in resource-limited settings: Clinical assessment".)

Growth charts for special populations — Special growth charts have been developed for a variety of conditions that are associated with altered patterns of growth. As examples:

●Down syndrome (see "Down syndrome: Management", section on 'Growth')

●Turner syndrome (see "Clinical manifestations and diagnosis of Turner syndrome", section on 'Short stature and skeletal anomalies')

●Cerebral palsy (see "Cerebral palsy: Evaluation and diagnosis", section on 'Nutrition and growth')

●Williams syndrome (see "Williams syndrome", section on 'Initial evaluation')

●Achondroplasia (see "Achondroplasia", section on 'Management')

●Prader-Willi syndrome (see "Prader-Willi syndrome: Management", section on 'Children and adults')

●Rett syndrome (growth charts) (see "Rett syndrome: Genetics, clinical features, and diagnosis", section on 'Growth failure')

RECOMMENDED GROWTH CHARTS WITH CALCULATORS

Infants 0 to 2 years — The Centers for Disease Control and Prevention (CDC) recommends using curves based on the World Health Organization (WHO) child growth standards for infants and toddlers under two years of age [7]. The related calculators use the same dataset and can be used to calculate Z-scores and percentiles.

●Recumbent length (figure 2A-B); (calculator 1)

●Weight (figure 3A-B); (calculator 2)

●Weight-for-length (figure 4A-B); (calculator 3)

●Head circumference (figure 5A-B)

Charts combining these curves are also available and may be most practical for clinical use:

●Weight-for-age and length-for-age (females, males)

●Weight-for-length and head circumference (females, males)

On these WHO charts, the normal range is generally defined as between -2 standard deviations (SD) and +2 SD (ie, Z-scores between -2.0 and +2.0), which corresponds to approximately the 2^nd and 98^th percentiles.

The WHO charts are thought to represent a healthier standard for children younger than two years of age because they are based on longitudinal measurements in a breastfed population. Use of the WHO charts is less likely to lead to miscategorization of a breastfed baby as being underweight compared with the CDC charts [7], although that may not be the case for infants younger than six months of age [8].

Children and adolescents 2 to 20 years — The CDC recommends using the CDC/National Center for Health Statistics (NCHS) growth charts for children two years and older [1,7]. The related calculators use the same dataset and can be used to calculate Z-scores and percentiles.

●Females:

•Standing height (figure 6A); (calculator 4)

•Weight (figure 7A); (calculator 5)

•Body mass index (BMI) (figure 8) (calculator 6), or extended BMI growth charts for those with severe obesity

●Males:

•Standing height (figure 6B); (calculator 7)

•Weight (figure 7B); (calculator 8)

•BMI (figure 9) (calculator 9), or extended BMI growth charts for those with severe obesity

Charts combining these curves are also available and may be most practical for clinical use:

●Weight-for-age and height-for-age (females, males)

●BMI (females, males)

On these charts, the normal range is generally defined as between the 5^th and 95^th percentiles, although additional categories are also used (eg, defining a category of "overweight" between the 85^th and 95^th percentile).

The above height-for-age curves reflect children with average timing of pubertal development. For selected children with early or delayed puberty, the appropriateness of current height and the child's height potential may be more accurately assessed by using curves selected for the child's stage of pubertal development. (See 'Special populations' below.)

When a child switches from the WHO to CDC charts around two years of age, this may cause some children to change categories. For example, a child may be classified as overweight on the WHO charts at 24 months but normal weight on the CDC charts. At the same time, the clinician should change from measuring recumbent length to standing height at 24 months of age to match the standard on which each chart is based. Measurements of recumbent length are approximately 1 cm greater than measurements of stature [7]. (See 'Length or height' below.)

Preterm infants — For preterm infants up to approximately 10 weeks post-term, other growth references should be used, as discussed in a separate topic review. After this age (or after hospital discharge), standard growth charts may be used but with corrections for gestational age. A traditional approach has been to correct for weight through 24 months of age, for stature through 40 months of age, and for head circumference through 18 months of age. (See "Growth management in preterm infants", section on 'Growth chart' and "Normal growth patterns in infants and prepubertal children", section on 'Correcting for prematurity'.)

SPECIFIC MEASUREMENTS AND TRAJECTORIES

Length or height — Length or height measurements require a firm, flat, horizontal, or vertical surface with perpendicular surfaces at each end [9].

Technique

●Children <2 years – Measure recumbent length.

•Technique – Measure using a length stadiometer (neonatometer) or tape measure, with the patient carefully positioned on a firm, flat surface (figure 10). Ideally, two people help to position the child [10]:

-The assistant (often the caregiver) positions the barefoot infant supine on the device with the head resting against the headboard and the neck in the midline.

-The child should be looking straight up, with the trunk and pelvis aligned with the measuring device.

-The examiner holds the infant's knees together and extends them by pressing down gently, brings the footboard up to touch the infant's heels, then reads the measurement of length to the nearest 0.1 cm.

•Growth charts (figure 2A-B).

●Children ≥2 years – Measure standing height (stature).

•Technique – Use a vertical stadiometer for optimal accuracy (figure 11). Proper positioning:

-The child's back is against the stadiometer.

-Head is midline, with neck straight.

-Feet are slightly apart, with back of heels touching the stadiometer.

-Middle of shoulders, buttocks, and back of head are touching stadiometer. Some participants may not be able to touch all four points against the stadiometer, due to obesity or curvature of the spine; if this occurs, have the participant touch two or three of the four points of the vertical surface of the stadiometer.

-Read height to the nearest 0.1 cm from the stadiometer.

•Growth charts (figure 6A-B).

For individuals ≥2 years who are unable to stand, recumbent length can be measured to estimate height, with the patient lying supine and flat. Recumbent length (when optimally measured) is generally slightly more than standing height [11]. For individuals with spinal deformities or extremity contractures, other techniques may be more accurate. (See 'Special populations' below.)

Length and stature should be measured to the nearest 0.1 cm [12]. Ideally, the measurement should be performed three times to improve accuracy and the mean should be plotted on a standardized growth chart.

Length and height measurements are particularly susceptible to variability due to operator error. Measurements that are not clinically plausible (eg, decreases in a child's height) should be repeated and corrected as necessary. These growth charts presume a transition from measuring recumbent length to standing height at two years of age. For a given individual, measured length is approximately 1 cm greater than standing height at age two years.

Interpretation — Short stature is defined by Z-scores or percentiles:

●Short stature – Short stature is usually defined as height Z-score <-2 (more than 2 standard deviations [SD] below the mean or approximately <2.3^rd percentile). (See "Diagnostic approach to children and adolescents with short stature".)

Less stringent definitions (eg, Z-score <-1.6 [<5^th percentile] or Z-score <-1.88 [<3^rd percentile]) are sometimes used as an indication for closer monitoring or evaluation or for treatment in high-risk groups such as children with chronic kidney disease [13]. (See "Growth failure in children with chronic kidney disease: Treatment with growth hormone".)

More stringent definitions (eg, Z-score <-2.25 [<1.2^nd percentile] or Z-score <-2.5 [<0.6^th percentile]) are sometimes used for other purposes, such as a threshold for considering growth hormone treatment in children with idiopathic short stature or those born small for gestational age. (See "Growth hormone treatment for idiopathic short stature" and "Growth hormone treatment for children born small for gestational age".)

●Severe short stature – Height Z-score <-3.

●Tall stature – Tall stature is defined as a height more than 2 SD above the mean for age (greater than the 97^th percentile). Tall stature has the same prevalence as short stature, but it is less commonly referred to subspecialty care. Common causes of tall stature include familial tall stature, obesity, Klinefelter syndrome, Marfan syndrome, and precocious puberty. (See "The child with tall stature and/or abnormally rapid growth".)

The evaluation and management of such a child differs with the clinical setting:

●Resource-abundant settings – If the child lives in a population where undernutrition is not common, the evaluation for short stature includes considerations of a variety of causes. (See "Diagnostic approach to children and adolescents with short stature".)

●Resource-limited settings – If the child lives in a population where undernutrition is common, then the evaluation and management focuses on this issue. (See "Malnutrition in children in resource-limited settings: Clinical assessment".)

Height velocity — Height velocity measurements are the most sensitive in detecting growth abnormalities early in the course of all types of chronic illness [14]. Incremental growth charts that characterize height and weight velocities over time can be used to more finely assess the growth rate of children, particularly those with specific clinical disorders [15-17].

During puberty, peak height velocity is 6 to 12 cm/year in males and 5 to 10 cm/year in females; the age of peak height velocity varies substantially (figure 12A-B). Any child older than two years whose height velocity is less than 4 cm/year should be monitored carefully for chronic nutritional deficits or causes of short stature because at least 95 percent of children grow faster than 4 cm/year [18]. (See "Diagnostic approach to children and adolescents with short stature".)

Special populations

●Children with early or delayed puberty – A series of Tanner stage-adjusted (TSA) height reference curves has been developed that reflects height-for-age at each stage of pubertal development, based upon data from the United States population [17,19]. The primary clinical utility of these curves is for:

•Children with short stature with late puberty for their age – This includes children whose puberty is delayed because of medical illness or puberty-suppressing therapy or constitutional delay of growth and puberty (a normal variant of pubertal timing). For these children, use of standard Centers for Disease Control and Prevention (CDC) height-for-age growth curves may exaggerate their degree of short stature. (See "Diagnostic approach to children and adolescents with short stature" and "Approach to the patient with delayed puberty".)

•Children with tall stature with early puberty for their age – For these children, use of standard CDC height-for-age growth curves may exaggerate their degree of tall stature. (See "The child with tall stature and/or abnormally rapid growth" and "Definition, etiology, and evaluation of precocious puberty".)

For these children, current growth status and growth potential may be more accurately assessed by using a TSA height reference, which is captured in this online calculator or by plotting the child's growth on a TSA-adjusted height-for-age growth curve, selected for their stage of pubertal development (sexual maturity rating) [19].

●Spinal deformity or extremity contracture – Alternative measurements to monitor linear growth for children with spinal deformities or extremity contractures include upper arm length and knee height [11,20-22]. Standard curves exist for these measurements [21,22]. Knee height is the distance from the surface of the thigh, just proximal to the patella, to the sole of the foot when the knee and the foot are bent at a 90º angle. Knee height is measured with a caliper designed for this purpose. Equations (Chumlea method) to estimate the height in cm from the knee-height measurement for children 6 to 18 years include the following [21]:

•White females: Height = 43.21 + (2.15 × knee height)

•Black females: Height = 46.59 + (2.02 × knee height)

•White males: Height = 40.54 + (2.22 × knee height)

•Black males: Height = 39.6 + (2.18 × knee height)

An alternative (Stevenson method) is to use the following equation (based on data from children with cerebral palsy and younger than 12 years of age) [23]:

•Height = 24.2 + (2.69 × knee height)

Children with severe cerebral palsy may have significant deviation from true length/height due to contractures or spinal deformities. Direct measurement of length in the supine position is the best way to accurately monitor growth in the clinical setting for some of these patients [24]. Another approach is to use growth charts specific to cerebral palsy. (See "Cerebral palsy: Evaluation and diagnosis", section on 'Nutrition and growth'.)

Weight

Technique — Weight measurements should be obtained on a scale that has been calibrated properly. The infant should be weighed naked and to the nearest 0.01 kg [12]. The older child should be weighed without shoes, in little or no outer clothing, and to the nearest 0.1 kg. The measurement should be plotted on a standardized growth chart (figure 3A-B and figure 7A-B).

Interpretation — The normal range for weight is generally defined as between the 5^th and 95^th percentiles on the CDC charts or a Z-score between -2 and +2 on the World Health Organization (WHO) charts.

However, these values are only meaningful when interpreted in conjunction with other growth parameters:

●Changes in weight over time (see 'Weight velocity' below)

●Weight-for-length for infants and toddlers (see 'Weight-for-length/height' below)

●Body mass index (BMI) for children ≥2 years (see 'Body mass index' below)

The effect of feeding method on the weight trajectory of infants is discussed separately. (See "Normal growth patterns in infants and prepubertal children", section on 'Effects of feeding method'.)

Weight velocity — Average weight gain in healthy children varies substantially by age:

●First year of life:

•Infants gain approximately 30 g/day between 0 and 3 months of age, 20 g/day between 3 and 6 months, and 10 g/day between 6 and 12 months

•Infants double their birth weight by four months of age and triple their birth weight by one year

●Ages two through early puberty – 2.5 kg/year

●Peak pubertal growth spurt – 1 to 4 kg/six months (but sometimes as high as 6 kg/six months)

Any prepubertal child whose weight velocity is less than 1 kg/year should be monitored carefully for progressive nutritional deficits because approximately 95 percent of children gain weight faster than this rate in a well-nourished population [25]. (See "Indications for nutritional assessment in childhood".)

Body mass index — BMI characterizes the relative proportion between the child's weight and height. It is a valid predictor of obesity and is therefore the best clinical standard for defining obesity in adults and in children older than two years of age.

Calculation — BMI is calculated as:

Interpretation — BMI in children must be compared with the population norms for age and sex, usually by using percentiles based on the CDC growth reference.

The BMI percentile is determined by plotting on a BMI reference chart or calculator:

●Females (figure 8); (calculator 6)

●Males (figure 9); (calculator 9)

The BMI percentile determines the weight category as follows (table 2):

●Underweight – BMI <5^th percentile

●Healthy weight – BMI ≥5^th to <85^th percentile

●Overweight – BMI ≥85^th to <95^th percentile

●Obesity – BMI ≥95^th percentile

●Severe obesity – BMI ≥120 percent of the 95^th percentile or ≥35 kg/m²

For children with severe obesity, special BMI charts with curves above the 97^th percentiles are useful for clinical evaluation and monitoring (figure 13 and figure 14), or extended BMI growth charts from the CDC. (See "Clinical evaluation of the child or adolescent with obesity".)

BMI standards for underweight are less well defined, but children with a BMI less than the 5^th percentile are underweight and should be evaluated and monitored for nutritional abnormalities. In undernourished adolescents, such as those with anorexia nervosa, BMI tends to underestimate the degree of undernutrition as compared with weight-for-height measurements [26]. However, no studies have examined whether one of these two methods better predicts clinical outcomes. Other methods can measure adiposity directly but have limited utility in the clinical setting. (See "Measurement of body composition in children".)

Weight-for-length/height

Technique

●Resource-abundant settings – In resource-abundant settings, weight-for-length is generally used for children zero to two years of age as an index of adiposity and to assess for overnutrition or undernutrition. The weight-for-length percentile can be determined by plotting the child's weight and recumbent length on a CDC chart (weight-for stature for girls or weight-for-stature for boys) or by using a calculator (calculator 3). After two years of age, BMI is generally used as an index of adiposity, as discussed above.

●Resource-limited settings – In resource-limited settings, weight-for-height is commonly used for children up to five years of age to assess undernutrition (malnutrition). The weight-for-length Z-score is determined by plotting the child's weight and length/height on the WHO chart (figure 15A-B) or by using the calculator (calculator 3).

Interpretation

●Underweight or moderate wasting – Z-score for weight-for-height/length <-2 (more than 2 SD below the mean). This corresponds to <2.3^rd percentile. However, milder abnormalities (weight-for-length <5^th percentile) should also raise concern for undernutrition and warrant evaluation and monitoring.

●Severe wasting – A Z-score <-3 (more than 3 SD below the mean). This corresponds to <0.1 percentile.

The evaluation and management of such a child differs with the clinical setting:

●Resource-abundant settings – If the child lives in a population in which undernutrition is not common, the evaluation focuses on diagnosing and treating other conditions that might be responsible for the poor weight gain. (See "Poor weight gain in children older than two years in resource-abundant settings", section on 'Diagnostic approach'.)

●Resource-limited settings – If the child lives in a population where undernutrition is common, then the management focuses on restoring nutrition and treating underlying infections. (See "Malnutrition in children in resource-limited settings: Clinical assessment" and "Management of moderate acute malnutrition in children in resource-limited settings" and "Management of uncomplicated severe acute malnutrition in children in resource-limited settings" and "Management of complicated severe acute malnutrition in children in resource-limited settings".)

Weight-for-length/height versus body mass index — Both BMI and weight-for-height can be used to predict adiposity, but the correlation depends in part on the child's age:

●Age 0 to 2 years – One study suggests an increasingly stronger correlation between BMI and weight-for-length from birth through 24 months of age [27]. BMI appears to be a better indicator of body composition (by plethysmography) at one month of age [28]. At two months of age, BMI has a stronger positive predictive value for obesity at two years of age than does weight-for-length, although their negative predictive values are similar [27]. This is likely due to the fact that BMI charts take age into account, whereas the weight-to-length charts do not. Perhaps in contrast, another study found little difference in BMI and weight-for-length in the prediction of obesity at 6, 12, and 18 months of age [29]. All three studies underscore the ability of BMI to predict early obesity [27-29]. (See "Poor weight gain in children younger than two years in resource-abundant settings: Etiology and evaluation", section on 'Measurement of growth'.)

●Age 3 to 5 years – For this age group, BMI-for-age and weight-for-height measures predict adiposity equally well. Nonetheless, BMI is generally used for assessing an overweight child because most risk thresholds and clinical recommendations have been based on the BMI percentiles (using the CDC reference charts).

●Age 6 to 19 years – For this age group, BMI for age is slightly better than weight-for-height in predicting adiposity using average skinfold thickness or dual-energy x-ray absorptiometry (DXA) as the standard [30]. (See 'Body mass index' above.)

Head circumference

Technique — Head circumference (also called fronto-occipital circumference) is measured at the maximum diameter through the glabella and occiput to the nearest 0.1 cm. The recorded value should be the mean of three measurements [12]. The measurement should be plotted on a standardized growth chart.

Head circumference is measured in children from birth to three years of age because this is the period of rapid brain growth. Head circumference also should be measured in older children with abnormal growth because it may be helpful in determining the etiology. A child with fetal alcohol syndrome, as an example, may have growth deficiency and microcephaly.

Interpretation — Head circumference is compared with a population standard for age and sex, with adjustments for gestational age when appropriate (figure 5A-B) (calculator 10).

●Microcephaly – Head circumference <-2 SD (2 SD or more below the mean) (see "Microcephaly in infants and children: Etiology and evaluation", section on 'Postnatal evaluation')

●Macrocephaly – Head circumference >2 SD (2 SD or more above the mean) (see "Macrocephaly in infants and children: Etiology and evaluation", section on 'Evaluation of postnatal macrocephaly')

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Poor weight gain in infants and children".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: My child is short (The Basics)" and "Patient education: Weight and health in children (The Basics)")

●Beyond the Basics topics (see "Patient education: Poor weight gain in infants and children (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Commonly used growth charts

•The growth charts developed by the Centers for Disease Control and prevention (CDC) were developed from measurements of a large multiethnic population living in the United States; they are considered a growth reference because they reflect norms within a population. (See 'Centers for Disease Control and Prevention growth reference' above.)

•The growth charts developed by the World Health Organization (WHO) describe normal growth from birth to five years under optimal environmental conditions, including breastfeeding, and are thus considered a growth standard. They can be applied to all children everywhere regardless of ethnicity, socioeconomic status, and type of feeding. Compared with the reference prepared by the CDC, the WHO standards result in lower estimates of undernutrition, except during the first six months of life, and higher rates of obesity. (See 'World Health Organization growth standard' above and 'Comparison' above.)

•Z-scores describe the degree to which a measurement deviates from the mean of a population (figure 1). The WHO growth standard uses Z-scores to define the normal range and cutoffs to define abnormal growth, whereas the CDC growth reference uses percentiles. The resulting categories of abnormal growth (underweight/overweight/obesity, short/tall stature) are similar but do not correspond exactly. On the WHO charts, the normal range is defined as Z-scores between -2.0 and +2.0 (ie, between -2 standard deviations [SD] below and +2 SD), which corresponds to the range between the 2.3^rd and 97^th percentiles. (See 'Use of Z-scores' above.)

●Recommended growth charts and calculators – For children in the United States, recommended growth charts are based upon WHO data for children younger than two years of age and on CDC data for those older than two years. These charts and related calculators can be used to determine percentiles or Z-scores. (See 'Recommended growth charts with calculators' above.)

•Infants 0 to 2 years:

-Recumbent length (figure 2A-B); (calculator 1)

-Weight (figure 3A-B); (calculator 2)

-Weight-for-length (figure 4A-B); (calculator 3)

-Head circumference (figure 5A-B)

•Females 2 to 20 years:

-Standing height (figure 6A); (calculator 4)

-Weight (figure 7A); (calculator 5)

-Body mass index (BMI) (figure 8) (calculator 6), or extended BMI growth charts for those with severe obesity

•Males 2 to 20 years:

-Standing height (figure 6B); (calculator 7)

-Weight (figure 7B); (calculator 8)

-BMI (figure 9) (calculator 9), or extended BMI growth charts for those with severe obesity

●Specific measurements and interpretation

•Length/height – Linear growth is determined by recumbent length in children <2 years and by standing height in children ≥2 years. Short stature is typically defined as a Z-score for height/length for age <-2 (more than 2 SD below the mean or approximately <2.3^rd percentile). A Z-score <-3 represents severe short stature. (See 'Length or height' above.)

•Height velocity – Changes in length/height over time (height velocity) is the most sensitive measure to detect growth abnormalities early in the course of all types of chronic illness. Height velocity should be at least 4 cm/year in a healthy child ≥2 years and typically reaches 5 to 10 cm/year during the peak pubertal growth spurt. (See 'Height velocity' above.)

•Weight-for-length/height – For children aged zero to two years, weight-for-length is generally used instead of BMI as an index of adiposity. Percentiles can be determined by plotting on a CDC chart (weight-for stature for girls or weight-for-stature for boys) or by using a calculator (calculator 3). Weight-for-length <5^th percentile should raise concern for undernutrition and warrants evaluation and monitoring. (See 'Weight-for-length/height' above.)

In resource-limited settings, weight-for-length/height is commonly used for children up to five years of age using the WHO chart (figure 15A-B) and categories of wasting based on Z-scores (figure 1). (See "Malnutrition in children in resource-limited settings: Clinical assessment".)

•BMI – For children 2 to 20 years, BMI is generally used as an index adiposity and to define weight categories including obesity (table 2). For children with severe obesity, special BMI charts with curves above the 97^th percentiles are useful for clinical evaluation and monitoring (figure 13 and figure 14) or extended BMI growth charts from the CDC. (See 'Body mass index' above.)