From the Guidelines
A head circumference of 19.2 inches for a 12-month-old child is generally within the normal range and not concerning. The average head circumference for a 12-month-old typically falls between 17.5 and 19.5 inches (44.5-49.5 cm), with most children measuring around 18.5 inches (47 cm) 1. Head circumference is an important measurement that healthcare providers track to monitor brain growth and development. At well-child visits, doctors plot these measurements on growth charts to ensure the child is following a consistent growth curve. What's most important is not a single measurement but rather the growth pattern over time. If a child's head has been growing steadily along their established curve, this measurement would be considered normal. However, if there has been a sudden increase or decrease in the growth rate, that might warrant further investigation regardless of the absolute measurement.
Some key points to consider:
- Macrocephaly, or a head circumference exceeding the mean for age and gender by at least 2 SD, is a clinical term that refers to a generalized increase in size of the head 1.
- The definition of macrocephaly is based on the occipitofrontal circumference (OFC) exceeding the mean for age and gender by at least 2 SD, which corresponds to the 97 percentile 1.
- Megalencephaly, on the other hand, refers to an increase in size of the brain, and may not necessarily imply macrocrania 1.
- Parents should continue with regular well-child visits where healthcare providers can monitor all aspects of growth and development, including head circumference, weight, and length.
It's also important to note that microcephaly, or a significant reduction in the occipitofrontal circumference (OFC) compared with controls matched for age and sex, is a different condition altogether, and is defined as an OFC that is 2-3 standard deviations below the mean 1. However, in this case, the head circumference of 19.2 inches is within the normal range, and not indicative of microcephaly. Regular monitoring of growth and development is essential to ensure that any potential issues are identified and addressed early on.
From the Research
Head Circumference Assessment
To assess whether a head circumference of 19.2 inches is concerning for a 12-month-old child, we need to consider the average head circumference for children at this age.
- The World Health Organization (WHO) provides standards for head circumference, but studies have shown that these standards may not be appropriate for all populations 2.
- A study on Argentine reference charts for head circumference found that the values for the 98th percentile were higher than those of the Nellhaus charts at all ages, while the values for the 2nd percentile were lower during the first 2 years of life 3.
- Another study found a relationship between head circumference and length in the first 400 days of life, which can be expressed by a simplified formula: head circumference (inches) = 0.5 length + 3.75 +/- 1 4.
- However, there is no direct evidence in the provided studies to determine whether a head circumference of 19.2 inches is concerning for a 12-month-old child.
Population-Specific References
- It is essential to use population-specific references when assessing head circumference, as the WHO standards may not be appropriate for all populations 2, 5.
- A study on Sri Lankan children found that the head circumference charts available in the Child Health Developmental Record (CHDR) were inappropriate for use in Sri Lankan children 5.
- Therefore, it is crucial to consult population-specific references or a healthcare professional to determine whether a head circumference of 19.2 inches is concerning for a 12-month-old child.
Neurological Outcomes
- A study on preterm infants found that the relative measurement of birth weight and head circumference was associated with neurological outcomes 6.
- However, this study does not provide direct evidence on the relationship between head circumference and neurological outcomes in 12-month-old children.