A simple calculation using a child's date of birth and body measurements can predict adult height, say researchers.
Child growth patterns vary considerably
Many children and their parents are interested to know how tall they will be as adults.
A hurdle has been accounting for an individual's biological maturity at the time of measurement - some children are early while others are late "bloomers".
A Belgian and Canadian team told the Journal of Pediatrics how they overcame this problem with a maths equation.
By adding a child's present height to how many centimetres the child still had left to grow they were able to predict the final height of boys within a 5.4 cm range and a 6.8 cm range for girls.
The researchers stress their tool can only make useful predictions for girls aged 8-16 and boys aged 9-18 and when body measurements such as sitting and standing height are taken accurately.
For years people have used the mid-parental height, which is the average of both parents' heights, as a crude prediction of that child's future adult height.
A child's adult height would be expected to fall within about 10cm of the mid-parental height.
Lauren Sherar colleagues from the University of Saskatchewan in Canada and the Faculty of Kinesiology and Rehabilitation Sciences in Belgium used a different technique that relies on the child's measurements.
They tested their tool on 224 boys and 120 girls aged 8-16 years.
Early or late bloomer
The first step in the prediction is estimating the child's growth maturity level.
Specifically, this is the how many years they child is from their peak height velocity (PHV) - the time when a child will have reached 92% of their adult stature.
This can be estimated from the child's age, sex, weight, sitting height and standing height.
From this, the child is classified as an early, average or late maturer.
Next, an estimate of the amount of growth remaining until adult height is calculated - the cumulative height value.
Adult height is then predicted by adding the child's height at the time of measurement to their predicted cumulative height value.
The researchers pointed out that because the predictive equations for age at peak height velocity and adult height are based on an average, white Caucasian population, predictions in other races may be associated with a degree of error.
Dr Charlotte Wright, consultant in community child health at Glasgow University, said that it would be difficult for a parent to accurately measure sitting height at home.
She also questioned how useful the prediction would be because the true adult height could be up to two inches bigger or smaller than the estimate.
However, she said that using serial measurements of a child's actual height was more accurate than using parental height to predict future growth and adult height.