What is a Neonatal Growth Chart?

A neonatal growth chart is a tool used by physicians to monitor the physical development of infants in the first month following their birth. The chart generally takes the form of a gender-specific graph which is marked with curves indicating a range of national or international percentiles for neonatal length, weight, and head circumference. Plotting an infant’s measurements on a neonatal growth chart allows physicians to monitor that infant’s growth rate and to determine how that rate compares to that of other infants of the same age. These charts can be useful in determining whether an infant’s growth is progressing normally.

Usually, a neonatal growth chart takes the shape of a graph which displays age on one axis and head circumference, weight, or length on its other axis. Instead of age, some versions may feature weight on one axis and length on the other. Often, a single neonatal growth chart actually features two graphs, one which shows head circumference for age data, and the other which shows either weight for length, weight for age, or length for age data. As girls and boys generally develop at different rates, the charts are gender-specific.

The graph of each neonatal growth chart is premarked with curved lines which indicate national or international percentiles for head circumference, length, and weight. In other words, it shows the normal range of measurements for neonatal infants in that country or in a number of similar countries, depending on the particular chart. By plotting an infant’s measurements on a chart, a physician can observe how the infant’s physical development compares to that of other infants. If the chart shows that the infant’s weight falls on the 90th percentile curve of the weight-for-age graph, for instance, that infant weighs more than 90 percent of infants of identical age.

It is critical to understand that, in isolation, these percentile figures do not always indicate whether a neonatal infant is healthy or unhealthy. Factors like heredity and nutrition can influence size, and an infant whose length falls on the 10th percentile curve, for instance, is not necessarily less healthy than an infant who falls on the 80th percentile curve. It is more important that an infant continues to follow roughly the same curve as he grows. In other words, a head circumference that continues to fall on the 5th percentile curve each time it is measured can be perfectly normal. Head circumference that suddenly jumps from the 5th percentile to the 50th percentile, on the other hand, may signal a developmental disorder.