Q. I have heard you can predict a child’s final adult height by doubling his height at age 2. Is this true?
Several factors play a role in determining a child’s final adult height, including genetics, gender, health and nutrition.
At each check-up, a child’s measurements are plotted on a growth chart to determine his percentiles for height and weight. After the first year of life, most children will develop a predictable growth pattern based on these percentiles. For example, if a boy is in the 50th percentile for height at ages 4, 5, and 6, then he will most likely be average height as an adult, but this is not always the case.
Children will continue growing until the growth plates in their bones fuse, which occurs at different ages for different children. This is the reason that some teens will stop growing at age 13 while others are still growing at age 17. Growth plate measurements can be used to determine a child’s “bone age.”
Children who are overweight or have early-onset puberty will typically have an advanced bone age and reach an adult at a younger age. There are other conditions that may delay a child’s bone age. These variables make height prediction based solely on growth charts less reliable.
Another common calculation based on genetics is something called a mid-parental height. This calculation is as follows:
(Mother’s height in inches + father’s height in inches) divided by 2. Add 2.5 inches for boys/ subtract 2.5 inches for girls.
The mid-parental height range is this number, plus or minus 2 inches.
The strategy of doubling a child’s height at age 2 for predicting his final height has not been proven accurate. In fact, the average girl is 34 inches tall at age 2. Double that, and she would grow to 5 feet 8 inches; the average adult height for a girl is 5 feet 4 inches.
In summary, it is important to monitor your child’s growth and development at regularly scheduled check-ups; however predicting a final height at a young age is difficult.