Previous studies suggest that low birth weight (< 2.5 kg [5.5 lb]) is associated with deficits in mental performance.1,2 Although potentially confounding factors are often ignored, consideration of other variables does not deny an association between low birth weight and poor mental performance.3-9
The problem of whether low birth weight is associated with deficits in mental performance in a developing country must be considered. It is difficult to draw inferences from one population to another since cause of low birth weight may not be the same in the two populations. Different types of low birth weight appear associated with different functional outcomes, such as different morbidity, mortality, and prevalence and type of behavioral abnormalities. Some low-birth-weight newborns may be relatively more impaired mentally than others. Harper and Wiener10 reported slightly lower intelligence quotients in low-birth-weight twins and triplets than in low-birth-weight singletons.
Most studies reporting a relationship