The level of cognitive functioning of children from very low-income families is below the lower limit of normal.

Particularly low levels of cognitive functioning are recorded in children under the age of 4, growing more slowly than their peers in a similar financial situation and requiring hospital treatment. At a later age, differences determined by growth rate disappear and the level of cognitive functioning depends mainly on the size of the family and its focus on the child's needs.

A six-year study, conducted on a group of 226 children (from birth to 6 years of age; newborns with birth weight within normal limits, without perinatal complications, congenital diseases or chronic illnesses) from very low-income families. 128 of them grew and developed more slowly than the other children and required hospital treatment.