How To Estimate The Weight Of Children Using Their Age

Child

The dose of drugs for adults is usually universal. However, the dose of drugs for infants and children is based on age and or weight. It is always easy to estimate age from looks. In other news, the age of the baby can be gotten from the parents or guardian. However, the weight of a baby can only be gotten by measuring it using a measuring scale. Estimation using looks can lead to fatal error in dispensing.
When parents or guardians want to treat a child in the hospital, they normally go with the child. The medical doctor may have the time to take the weight at the office before prescription. There are times this may not be possible. A medical doctor may not have all the time in the world to take the weight of an acutely unwell child that require rapid resuscitation and stabilization.
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The problem is more pronounce in retail or community pharmacy settings. Most parents or guardians come to the pharmacist without bringing the child along and hoping for a proper diagnosis and treatment. At this stage the pharmacist is left with no other choice than to use an estimation of the baby's weight to dispense.
With just the age of the child gotten from the parents or guardians, can one accurately to the nearest degree predict the weight of the child? The answer lies in the following paragraphs.

World Health Organization (W.H.O) Chart

The world health organization (WHO) have an accurate chart that estimate the weight of children based on weight at birth and age. It provides a curve for each weight at birth for both boys and girls. A boy that weights 10kg at birth may weight about 12kg after a month. However, another boy that weights 5kg at birth is expected to weight less than the first after a month. It should be about 7kg. The chart covers for children of both sexes from age 0-5.
The WHO chart is very good and important. It is very handy. However, it is not really a good idea to always look at a chart everytime something like this comes up. The best is to find an alternative.
Here is a link to WHO chart

Advance Pediatric Life Support (APLS) Formula

The APLS formula have been confirmed to work well for children in develop countries. The accuracy for children between the ages of 1-5 years is high. It is advisable that it should not be use for children below 1 years and above 5 due to the great deviation from the normal. It's mean underestimate score is more than 20% at age 10 years.
Weight (in kg)=(age in years+4)×2
Example: a child of 2 years is expected to weigh 12kg from the calculation.

United Kingdom (U.K) Standard

The UK make use of two different formula. Named luscombe and Owens' formula, it caters for the estimation of children's weight between the age of 1-16 years of age. The first formula is;
Weight (kg)=3×(age in years)+7
This formula provided a mean underestimate of 6.9%. This formula is applicable to children between 1-13 years of age. However, others believe that it is best to use it for children between 6-12 years alone.
The second formula is;
Weight (kg)=2×(age in years+4)
It is believe to underestimate children's weight by a mean of 33.4% over 1-16 years of age.
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Australian Formula

An Australian researcher use the weight value of more than 70000 children to derive series of formula. They are;
1. Infants less than 12 months: weight (kg)=(age in months+9)÷2
2. 1-5 years: weight (kg)=2×(age in years+5)
3. 5-14 years: weight (kg)=4×age in years
However, the most accurate ones are practically not possible to use in cases of emergency. For example the formula derived by a researcher in Trinidad and Tobago worked out a formula, weight=(2.5×age in years)+8. Though adjudged to be accurate, it is difficult to calculate the weight of a child in urgent situation without the use of an electronic or digital calculator. Another that fell into this category is;
Weight (kg)=2.4×age in years+8.25 which have been found to be the best of all. But it is difficult to start estimation without using an electronic or digital calculator.
Due to the near to accuracy of the one from Trinidad and Tobago, using a little alter version of it have proven to be very effective in estimating weight by age. The formula is;
Weight (kg)=2n+8
Where n is age in years.
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