From the Guidelines
To calculate height velocity for a 9-month-old, measure the baby's length accurately at two points in time, typically 3-6 months apart, and divide the change in length by the time interval, using the World Health Organization (WHO) growth charts as the standard for children under 24 months, as recommended by the CDC 1. When calculating height velocity, it is essential to use a proper infantometer with the baby lying flat, legs extended, and head positioned properly. The same measuring device should be used each time, and ideally, the same person should perform the measurements to minimize error.
- Height velocity is a valuable tool for monitoring growth, as it can detect growth problems earlier than single measurements plotted on growth charts.
- Normal height velocity for infants 6-12 months old is approximately 1.5 cm per month, and if a baby's height velocity falls significantly below expected rates (less than 0.7 cm per month at this age), consultation with a pediatrician is recommended. The WHO growth charts are based on the growth of healthy children in optimal conditions, with 100% of the reference population of infants breastfed for 12 months and predominantly breastfed for at least 4 months, making them a suitable standard for assessing growth in children under 24 months 1.
- The CDC recommends using the 2006 WHO international growth charts for children aged <24 months, rather than the CDC growth charts, for assessing growth in clinical settings in the United States 1.
- When using the WHO growth charts to screen for possible abnormal or unhealthy growth, use of the 2.3rd and 97.7th percentiles (or ±2 standard deviations) are recommended, rather than the 5th and 95th percentiles.
From the Research
Calculating Height Velocity
To calculate the height velocity of a 9-month-old child, we need to consider the average growth rate of children at this age.
- The provided studies do not directly address the calculation of height velocity in 9-month-old children.
- However, studies such as 2, 3, and 4 discuss growth hormone deficiency in children, which can affect their growth rate.
- According to 4, brain magnetic resonance imaging (MRI) may be used to diagnose growth hormone deficiency in early childhood, but it does not provide information on calculating height velocity.
- Study 5 examines the relationships between MRI findings and clinical/hormonal phenotypes in children with growth hormone deficiency, but it also does not provide information on calculating height velocity.
Growth Hormone Deficiency
- Growth hormone deficiency can affect the growth rate of children, as discussed in studies 2 and 3.
- The diagnosis of growth hormone deficiency is crucial in children with short stature, as initiating treatment with recombinant human GH can help them attain their genetically determined adult height 2.
- However, the provided studies do not offer a formula or method for calculating height velocity in 9-month-old children.
Limitations
- There are no research papers provided that directly assist in answering the question of calculating height velocity in a 9-month-old child.
- The studies provided focus on growth hormone deficiency, its diagnosis, and management, but do not address the specific question of calculating height velocity.