The disparity in BMI between urban and rural areas remained modest over the three decades, with a maximum difference of less than 1.4 kg/m² across all countries and years and less than 1.1 kg/m² ...

Stages of child development are important measures of growth and maturity. There are many tools to measure development. Here's a list of developmental milestones.

See e.g. Jay N. Giedd et al., “Brain Development During Childhood and Adolescence: A Longitudinal MRI Study,” Nature Neuroscience, Vol. 2, p. 861, 1999 (MRI study of the brains of 145 children ...