One technique for estimating the weight of children in emergency situations is to use the simple rule:
| Age (yrs) | 1 | 3 | 5 | 7 | 9 |
| Estimated Weight (kg) | 10 | 15 | 20 | 25 | 30 |
This simple pattern makes it easier to remember.
To test the validity of this rule-of-thumb the weight measurements from children aged 0 - 9yrs were
retrospectively collected from our practice records for the preceding 10 yrs and plotted
to produce the following graph:
Plotted in red is the non-parametric non-linear model and, in blue, the linear regression model
for the data. The black triangles plot the weight estimation points.
Below is the estimations tabled:
| Age (yrs) | 1 | 3 | 5 | 7 | 9 |
|---|---|---|---|---|---|
| Estimated Weight (kg) | 10 | 15 | 20 | 25 | 30 |
| LOESS Model Predicted Weight (kg) | 9.8 | 15.6 | 19.9 | 25.6 | 33.4 |
| Linear Regression Model Predicted Weight (kg) | 9.4 | 15.0 | 20.5 | 26.0 | 31.6 |
Conclusion:
The quick rule-of-thumb estimation of children's weight underestimates weight by 1-3kg in children older than 7.
Analysis age 0 - 12 months:
Below is a linear regression and non parametric plot of weights from 0-12 months.
The gradient of the linear regression model is 0.4976
This model suggests the the mean weight gain from age 0-12m is:
~500 g/month (~16g/d)
