How Tall Will I Be?
"How tall will I be?" or "how tall will my child be?" are questions that are often asked. The height of a person is determined by a combination of genetics and environmental factors. The precise contribution from these two factors is complex, but some studies suggest that genetics contributes 60%-80%.
Normally, a child's height is based on parental heights subject to regression toward the mean. This means that very tall or short parents are likely to have a taller or shorter child than average, but the child is likely to be closer to the average height than their parents.
Other important factors that contribute to a child's adult height include nutrition, health, sports activities, and the health and age of the mother during pregnancy.
The Human Growth Cycle
Infants and toddlers grow the fastest. The growth rate declines rapidly from birth to roughly age 2 and declines more slowly thereafter. During puberty, the growth rate increases again to a second maximum, after which it slowly declines to zero. This is typically referred to as the pubertal growth spurt. On average, female and male growth trails off to zero at about 15 and 18 years old, respectively.
In some cases, a person's height begins to shrink in middle age, though shrinkage of stature is largely universal in the very elderly. This is due to factors such as the decreased height of intervertebral discs as well as changes due to degenerative diseases.
Methods for Predicting a Child's Adult Height
Many different methods have been developed to predict a child's adult height, some more accurate than others. Regardless of how accurate the method, height prediction is not an exact science, and it is possible that a child's height can deviate significantly from what is predicted.
1. Bone Age / Skeletal Maturity Method
Bone age can be used to predict height and is considered highly accurate. One such method is the Greulich-Pyle method that involves left hand and wrist radiographs (X-rays) to measure bone age. This method compares the radiograph of the patient to that of the nearest standard radiograph in the Greulich-Pyle atlas. Based on bone age and current height, it is possible to predict final height based on the percentage of growth remaining.
2. The Khamis-Roche Method
The Khamis-Roche method is considered to be one of the more accurate height prediction methods that do not require the measurement of bone age. It is based on the child's stature, weight, and the average stature of the two parents. The primary calculator above uses a variation of this method.
Note: It is most applicable to Caucasian children between the ages of 4 and 9 who are free from any growth-related condition or disease.
3. Using CDC Growth Charts
CDC Growth Charts of the United States are excellent sources of information to evaluate the growth situation of a child. These charts consist of percentile curves illustrating the distribution of specific body measurements. Because children generally maintain a fairly constant growth curve (e.g., staying near the 50th percentile), these charts can be used to predict adult height by following the curve to age 20.
4. Simple Mid-Parental Method
There are also some very simple, but less accurate, methods available. One of them is adding 2.5 inches (7.6 cm) to the average of the parents' height for a boy and subtracting 2.5 inches (7.6 cm) for a girl. The second calculator above is based on this genetic potential method.
How to Maximize Your Growth Potential
Height, for better or for worse, is largely determined by genetics. After the growth spurt during puberty, neither sex will typically grow much more. However, environmental factors during childhood and adolescence can affect whether a child reaches their full genetic height potential.
- Nutrition: Eat as many unprocessed foods as possible such as fresh fruits, vegetables, whole grains, proteins, and dairy. Avoid foods high in sugar, trans fats, and sodium.
- Exercise: Exercise regularly to strengthen bones and muscles, maintain a healthy weight, and reduce the risk of diseases.
- Posture: Pay attention to good posture. Aside from looking shorter due to poor posture, it can affect actual height in the long term if the back starts curving to accommodate a regular slouching posture.
- Sleep: Sleep regularly. Human growth hormone (HGH), a crucial factor that affects growth, is released while you sleep in deep cycles. A regularly poor sleeping schedule during adolescence can affect growth in the long term.
References:
1. Mari Satoh, "Bone age: assessment methods and clinical applications", Clinical Pediatric Endocrinology, 2015
2. Khamis HJ, Roche AF, "Predicting adult stature without using skeletal age: the Khamis-Roche method", Pediatrics, 1994