Predicting children's final height

Tots to Teens

September 10, 1996|By Dr. Modena Wilson and Dr. Alain Joffe | Dr. Modena Wilson and Dr. Alain Joffe,SPECIAL TO THE SUN

How do you know when you have reached your lifetime growth or height, meaning if you will get any taller or stay the same height?

It's not easy to be sure exactly when you will stop growing, nor is it straightforward to say exactly how tall a teen-ager will be when he or she finishes growing. But we can tell you a bit about the growth process and about what to expect as you go through puberty.

On average, both boys and girls gain about 25 to 35 centimeters during this time, which represents about 25 percent of their adult height. The normal growth spurt lasts about 24 to 36 months. However, there is a considerable variation among teen-agers. During their year of maximum growth, girls can grow as little as 5.4 or as much as 11.2 centimeters. For boys, the range is 5.8 to 13.1 centimeters.

The growth pattern for girls and boys is different in other ways.

You may have noticed that in middle school, girls tend to be taller than boys. This is because girls start to mature ahead of boys and enter their growth spurt ahead of them.

The timing of the maximum point of growth is generally about one year after the onset of breast development, the first sign of puberty.

By the time a girl has begun to menstruate two years later, she has all but completed her growth. She may grow an additional one or two inches.

Boys tend to reach their maximum growth about two years after they start to develop. There is no specific marker for boys that signals the end of growth. Hence, it is a little more difficult to say with certainty when a boy has stopped growing.

There are a number of ways to predict a teen-ager's final adult height.

One is to take an X-ray of the wrist. The pattern of the bone growth centers seen on X-ray determines an individual's skeletal age (maturity of the bones). Standardized tables can then predict final adult height, based on a teen-ager's current age and height and the difference between their true age and their skeletal age. The greater the difference between these two ages, the larger the potential for growth.

Other growth curves yield a prediction of adult height based on current age and height and the teen-ager's physical maturity.

Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.

Pub Date: 9/10/96

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