Baby growth charts are regularly used by pediatricians and parents as a part of determining the health of a baby. The charts display a range of values for weight, height, and head circumferences based on age and gender. A single percentile is assigned for each factor being evaluated as shown on a curve. For a user to determine a baby’s percentile, they would locate the baby’s age and specific personal data, such as the baby’s actual weight, and find the place on the curve where these two points meet. It’s important for parents to become familiar with and to use baby growth charts to ensure that their child is growing at the expected rate. Not having adequate growth could indicate issues such as an underlying condition or improper feeding habits. Growth charts along with the expertise of a pediatrician can help address any growth issues that may arise.
Baby growth charts were developed by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). The CDC’s growth charts were based on analyzing data to indicate how children grew in the United States during a specific time frame. The WHO’s growth charts are provided to indicate how children grow under ideal conditions, which includes being mainly breastfed for at least four months and continuing to breastfeed at the age of 12 months. Due to this difference, the CDC recommends that the WHO’s growth charts be used for children under two years old. The WHO has four different charts for each gender. The charts compare weight and length, head circumference and age, length for age, and weight for age. The WHO’s growth charts can be found online where two charts are placed on one page or a simpler version where only one chart is placed on one page. The WHO growth charts use kilograms and centimeters for measurements. The CDC provides the WHO’s growth charts with pounds and inches as measurements, in addition to kilograms and centimeters, since these are the common measurements that are used in the United States.
To properly make comparisons among babies, percentiles are used. Percentiles are used by taking a large quantity of data, placing them into 100 equal categories, and ranking the data. These categories are referred to as percentiles and range from zero to 100, with zero being the lowest ranking data and 100 being the highest ranking data. The WHO growth charts do not list every possible percentile but rather the select few of second, fifth, 10th, 25th, 50th, 75th, 90th, 95th, and 98th percentile. For example, a three-month-old baby girl that weighs 10 pounds would be in approximately the second percentile. The percentile was found by using the CDC’s version of the WHO’s growth chart for girls aged birth to 24 months that show length-for-age and weight-for-age percentiles. To begin, the age in months, that was three months in the example, is located at the bottom of the chart on the horizontal axis. Then, the weight in pounds, that was 10 pounds in the example, is located on the left side of the chart on the vertical axis. The point on the chart where three months and 10 pounds meet is closest to the curved line labeled with the number two, which is the percentile. To be in the second percentile on this chart indicates that only two percent of all three-month-old baby girls weigh less than the baby that was weighed in the example. To be considered a part of the average population, a baby would have to have a percentile somewhere in between the 25th and the 75th percentile. Therefore, the baby’s placement in the second percentile would indicate that the child is underweight.
During the few years of life, babies are frequently being measured to ensure adequate growth. A baby is measured on the day that they are born. Then, they are usually measured when babies are taken to the pediatrician’s office for their scheduled wellness checkups. According to the American Academy of Pediatrics (AAP), these checkups should occur when babies are three to five days old, one month old, two months old, four months old, six months old, nine months old, 12 months old, 15 months old, 18 months old, 24 months old, and 30 months old. Then, once a child is three years old, their growth will be checked during the wellness visit that occurs once per year. Babies not showing adequate growth will be measured more frequently than the recommended schedule. This usually occurs as modifications are made to whatever underlying issue is present that is negatively impacting the baby’s growth.
Babies are born with different weights, heights, and head circumferences. Yet, these figures generally stay in a specific range that is considered normal. Similarly, babies grow at different rates. Yet, growth rates tend to stay within a specific range. The Mayo Clinic provides a general estimate of what to expect in regards to growth for a baby during the first year of life. Generally, babies from birth until six months grow about one-half to one inch per month in height and gain about five to seven ounces in weight per week. Babies from six months until 12 months grow about three-eighths of an inch per month in height and gain about three to five ounces per week in weight. According to John Hopkins Medicine, a baby’s head circumference increases by about one-half of an inch each month during the first six months, one-fourth of an inch each month between the seventh and ninths month, and one-half of an inch each month between the 10th and 12th months.
Baby growth charts provide key indicators that compare a single baby’s information with that of the larger population of babies. Combined with other indicators, baby growth charts can be very helpful to both pediatricians and parents in determining the health of a baby.