Dimitri A. Christakis of the Seattle Children's Research Institute and the University of Washington warns parents to limit the amount of television children watch before the age of 2. He also expresses concerns about DVDs aimed at infants that claim to be beneficial, despite a lack of scientific evidence.

The review looked at 78 studies that examined the effect that TV has on children's language, cognitive skills and attentional capacity.

The review found as many as 9 in 10 children under the age of 2 watch TV regularly, despite ongoing warnings, and some spend as much as 40 percent of their waking hours in front of a TV.

The review, published in Acta Paediatrica, said watching TV programs or DVDs aimed at infants can delay language development and while infants will imitate what they see on a TV screen but they learn better from live presentations,

"The weight of existing evidence suggests the potential for harm and I believe that parents should exercise due caution in exposing infants to excessive media," Christakis says in a statement.

"We believe TV exposes children to flashing lights, scene changes, quick edits and auditory cuts which may be over stimulating to developing brains, while TV also replaces other more important and appropriate activities like playing or interacting with parents."