Nine out of 10 children under the age of 2 watch TV, DVDs and videos regularly, according to researchers at the University of Washington cited in the Archives of Pediatrics and Adolescent Medicine.
The researchers also found that as many as 40% of infants younger than 3 months put in daily TV time.
At 3 months, children watched less than an hour per day, but were up to an hour and a half by 24 months.
About half of the shows were educational, while the other half were split evenly among non-educational kid shows, baby DVDs/videos and adult TV.
Nearly three in 10 parents surveyed believed baby-oriented TV and DVD programs offered educational benefits.
"We don't know from the study whether it is good or bad. What we know is that it is big," said Frederick Zimmerman of the University of Washington.