Parents might be quick to cue up an educational app on their tablet or smartphone to soothe a crabby toddler, but a recent study from the University of Michigan shows that may not be such a great idea.

According to a study by Michigan Medicine published in the Journal of Developmental and Behavioral Pediatrics, 95 percent of the 135 apps the research team reviewed contained at least 1 advertisement targeting children.

The University of Michigan’s C.S. Mott Children’s Hospital found at least one type of advertising in 129 of the 135 apps designed for children aged 5-and-under. All of the free apps were supported by ads, and perhaps surprisingly, 88 percent of paid apps also included advertising aimed at young children.