I’m an individual
Once more for those up the back: nobody is awarding points to the biggest baby! The whole point of a growth chart is to show the range which children at any given age may measure. Height, weight and head circumference are the common measurements.
You can anticipate what a baby aged X months might weigh if they are a particular height but there are lots of reasons why they might not hit that mark on a particular day or even week. Even siblings can be significantly different in how they grow. Detailed studies tracking individual weight gain daily show it is typical for growth to occur in fits and starts.
It is the individual curve over time which matters most, not where a child's curve sits compared to others.
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In 2006, the World Health Organization released international growth charts depicting the growth of children from birth to 5 years who had been raised in six different countries (Brazil, Ghana, India, Norway, Oman, and USA) according to recommended nutritional and health practices.
The optimal growth displayed in these WHO growth charts represents the prescribed gold standard for children’s growth or the way all healthy children should grow.
Breastfed infants were used as the normative model for growth and development so the growth patterns will align with current recommended feeding practices.