Short answers, pulled from the story.
A child whose height-for-age value falls at least two standard deviations below the median of the World Health Organization's Child Growth Standards is defined as stunted. This threshold establishes a clear measure for impaired growth and development in early childhood.
Almost all stunting occurs within the 1,000-day period that spans from conception to a child's second birthday. The condition is largely irreversible if it happens during this window because interventions must happen before age two to prevent permanent physical consequences.
More than 85% of the world's stunted children live in Asia and Africa with sub-Saharan Africa seeing 40 per cent of children under 5 years of age affected. The four countries with the highest prevalence are Timor-Leste, Burundi, Niger and Madagascar where more than half of children under 5 years old are stunted.
Poor maternal nutrition during pregnancy is a primary driver as low maternal BMI predisposes the fetus to poor growth. Women who are underweight or anemic during pregnancy are more likely to have stunted children.
On a societal level it has been estimated that stunting can affect a country's GDP by up to 3%. This economic loss results from reduced cognitive achievement and career performance among stunted individuals.