The head circumference-for-age is typically used together with other growth indices to assess infants’ growth and development. It is often used in clinical settings as part of health screening for potential developmental or neurological disabilities in infants and young children.
Growth chart
Growth charts are used to compare your child’s height, weight, and head size against children of the same age.
Growth charts can help both you and your health care provider follow your child as they grow. These charts may provide an early warning that your child has a medical problem.
Growth charts were developed from information gained by measuring and weighing thousands of children. From these numbers, the national average weight and height for each age and gender were established.
The lines or curves on growth charts tell how many other children in the United States weigh a certain amount at a certain age. For example, the weight on the 50th percentile line means that one half of the children in the United States weigh more than that number and one half of the children weigh less.
WHAT GROWTH CHARTS MEASURE
Your child’s provider will measure the following during each well-child visit:
- Weight (measured in ounces and pounds, or grams and kilograms)
- Height (measured while lying down in children under age 3, and while standing up in children over age 3 and older)
- Head circumference, a measurement of the head size taken by wrapping a measuring tape around the back of the head above the eyebrows
Beginning at age 2, a child’s body mass index (BMI) can be calculated. Height and weight are used to figure out the BMI. A BMI measurement can estimate a child’s body fat.
Each of your child’s measurements is placed on the growth chart. These measurements are then compared with the standard (normal) range for children of the same sex and age. The same chart will be used as your child grows older.
HOW TO UNDERSTAND A GROWTH CHART
Many parents worry if they learn that their child’s height, weight, or head size is smaller than those of most other children the same age. They worry about whether their child will do well in school, or be able to keep up in sports.
Learning a few important facts can make it easier for parents to understand what different measurements mean:
- Mistakes in measurement can happen, for example if the baby squirms on the scale.
- One measurement may not represent the big picture. For example, a toddler may lose weight after a bout of diarrhea, but will likely regain the weight after the illness is gone.
- There is a wide range for what is considered “normal.” Just because your child is in the 15th percentile for weight (meaning 85 out of 100 children weigh more), this number rarely means your child is sick, you are not feeding your child enough, or your breast milk is not enough for your baby.
- Your child’s measurements do not predict whether they will be tall, short, fat, or skinny as an adult.
Some changes to your child’s growth chart may worry your provider more than others:
- When one of your child’s measurements stays below the 10th percentile or above the 90th percentile for their age.
- If the head is growing too slowly or too quickly when measured over time.
- When your child’s measurement does not stay close to one line on the graph. For example, a provider may worry if a 6-month-old was in the 75th percentile, but then moved to the 25th percentile at 9 months, and dropped even lower at 12 months.
Abnormal growth on the growth charts is only a sign of a possible problem. Your provider will determine whether it is an actual medical problem, or whether your child’s growth just needs to be watched carefully.
Head Circumference Chart
Head circumference (HC) is a measurement of the head around its largest area, typically measured on infants and children until the age of five years as part of routine child care. It measures the distance from above the eyebrows and ears and around the back of the head.
In children, this measurement forms part of a growth assessment to provide information on health, development and nutritional status (other measurements include height and weight). HC and the ratio between HC and weight for example, may also detect any abnormal brain or skull growth (e.g. hydrocephalus, microcephaly, macrocephaly).
HC is a simple, inexpensive and easily accessible tool for monitoring brain development and identifying infants at risk of neurodevelopmental disorders (Garcia-Alix et al., 2004). HC is often used in infants born small for gestational age (SGA). SGA babies and infants with a birth weight less than the 10 th percentile are at an increased risk of perinatal morbidity, continued short stature, and metabolic alterations later on in life (Cho and Suh, 2016). Studies have shown that SGA infants present with a higher rate of growth for head circumference compared to their appropriate for gestational age (AGA) peers – i.e. SGA infants try to catch-up with AGA infants to undo the effects of nutritional insult experienced during gestation (Kaur et al., 2011).
HC is typically measured using a flexible but non-stretch tape, such as the Seca 212 measuring tape or Lasso-o Child Growth Foundation tape. The tape measure should be checked for correct assembly and any damage before each use.
Protocol
- The child should be standing, seated or seated on parent/guardian’s lap depending on age and ability.
- Any hair ornaments or braiding should be removed if possible.
The tape should then be placed over the child’s head above the ears and eyebrows on the most anterior protuberance of the forehead (frontal bone) and around the occipital prominence at the back of the head.
- Aim to measure the largest circumference possible
- The tape should be pulled tight so that any hair is compressed
- The measurement should be read and recorded to the nearest millimetre
- Repeat the measurement and if there is a difference of >0.5cm, a third should be taken
- The tapes typically show both centimetres and inches, ensure that the measurement is taken using the metric scale
- If the infant/child has an abnormally shaped head (eg. craniosynostosis or a low airline (Saethe-Chotzen syndrome), ensure that the tape is placed over the largest measurable circumference
- HC should not be carried out before 36 hours of age due to scalp oedema, preferably to be assessed at 7-10 days of age
HC is used in clinical practice, in nutritional surveys and in epidemiological studies in combination with other anthropometric measures such as height and weight to provide an assessment of growth and development.
The relationship between HC and weight for example can identify if there is a need for further monitoring or investigation; a small head circumference with a low weight needs a different approach compared to a small head with a normal weight (GOSH Clinical Guidelines Online, 2017). Some studies have shown that HC standard deviation scores (or Z-scores) are highly correlated with those for height and weight, and this suggests that body size should be taken into account when interpreting the HC of a child (Geraedts et al., 2011).
Plotting HC on child growth standard charts can give an immediate indication of whether the child’s head, and therefore brain, is growing and a rate which is expected.
Growth Charts
Standardized growth charts are used to plot HC each time it is measured throughout the first years of life. This can show how HC is changing over time and can highlight if HC is increasing too quickly or not quick enough.
The World Health Organization provides access to such charts up to the age of 5 years:
- Head circumference-for-age Girls (birth to 5 years)
- Head circumference-for-age Boys (birth to 5 years)
However, these charts must be interpreted together with age and special consideration must be taken for infants who were born prematurely. For example, an infant born 6 weeks early (at 34 weeks gestation) will have a corrected age of 6 weeks less than his/her actual age since birth. Their measurements should be plotted on the chart at their actual age, with a horizontal line drawn back to their corrected age. Adjustments for prematurity to be made until they reach one year of age. Early year UK WHO growth charts (rcpch.ac.uk)
The head circumference-for-age is typically used together with other growth indices to assess infants’ growth and development. It is often used in clinical settings as part of health screening for potential developmental or neurological disabilities in infants and young children.
This index is expressed in percentiles (percentage of median) and can be assessed by the percentile point achieved by a child relative to the healthy children of that age and gender in the same population. Median is regarded as a reference value, and 3 rd and 97 th percentiles as thresholds to indicate abnormally low or abnormally high values.
It can also be expressed as a Z-score derived by using the formula:
(Measured value – Average value in the reference population) / Standard deviation of the reference population
The WHO growth standard for head circumference for age is used for its interpretation.
Typically, an infant with a HC >97 th percentile is considered to present with macrocephaly, while a HC of
An overview of head circumference methods is outlined in Table 1.
- Quick to measure
- Non-invasive
- Easily accessible, inexpensive equipment
Limitations
- Sometimes difficult to measure on non-cooperative infants
- Requires access to growth charts and/or other measures for interpretation of results
- Inaccurate to measure before 36 hours of age due to scalp oedema
Table 1 Characteristics of head circumference methods.
| Characteristic | Comment |
|---|---|
| Number of participants | High |
| Cost of development | Low |
| Cost of use | Low |
| Participant burden | Low |
| Researcher burden of data collection | Low |
| Researcher burden of coding and data analysis | Low |
| Risk of reactivity bias | No |
| Risk of recall bias | No |
| Risk of social desirability bias | No |
| Risk of observer bias | Yes |
| Participant literacy required | No |
| Cognitively demanding | No |
| Suitable for use in the field | Yes |
Considerations relating to the use of head circumference methods in specific populations are described in Table 2.
Table 2 Use of head circumference methods in different populations.
| Population | Comment |
|---|---|
| Pregnancy | Typically used in infancy and childhood, but it is suitable to use in this population. |
| Infancy and lactation | Suitable. |
| Toddlers and young children | Suitable. |
| Adolescents | Typically used in infancy and childhood, but it is suitable to use in this population. |
| Adults | Typically used in infancy and childhood, but it is suitable to use in this population. |
| Older Adults | Typically used in infancy and childhood, but it is suitable to use in this population. |
| Ethnic groups | Suitable as WHO HC for age can be used in infants and children of different ethnic backgrounds. |
| Other (obesity) | Typically used in infancy and childhood, but it is suitable to use in this population. However, it can be used in overweight and obese children and infants. |
- Head circumference tape (in cms)
- WHO Growth Charts
- Data entry form (either paper or computerised)
- Trained research staff
- Standard operating procedures for data collection
- Standard operating procedures for data entry and data cleaning
A method specific instrument library is being developed for this section. In the meantime, please refer to the overall instrument library page by clicking here to open in a new page.
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- Clayton PE, Cianfarani S, Czernichow P, Johannsson G, Rapaport R, Rogol A. Management of the child born small for gestational age through to adulthood: a consensus statement of the International Societies of Pediatric Endocrinology and the Growth Hormone Research Society. J Clin Endocrinol Metab. 2007 Mar;92(3):804-10. PubMed PMID: 17200164. Epub 2007/01/04. eng.
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- gosh.nhs.uk
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- National Institute for Health Research SBRC. Proceedure for Measuring Circumferences in Children 2015. Available from: http://www.uhs.nhs.uk/Media/Southampton-Clinical-Research/Procedures/BRCProcedures/Procedure-for-circumference-measurements-of-children.pdf.
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