What could be more wholesome than the sight of a parent scooching down a playground slide while holding a giggling toddler in their lap? It’s all fun and games until someone gets seriously hurt.Think that’s an overstatement? New research found 352-thousand children less than 6 years of age were injured on slides in the United States from 2002 through 2015.

Children ages 12 to 23 months had the highest percentage of injuries, the most common of which was a broken leg. Researchers at the University of Iowa Carver College of Medicine used the National Electronic Injury Surveillance System, which collects injury data from emergency departments across the nation, to examine factors associated with slide-related injuries in young children. They found most injuries are lower extremity fractures that happened while sliding down on another person’s lap. This almost always happened when the child’s foot caught the edge or bottom of the slide, then twisted and bent backward.

Researchers said the size and weight of the adults are important. A young child sliding alone is unlikely to get seriously hurt even if their foot catches on the slide because of the low amount of force involved. But the increased force generated by the momentum of the adult carrying the child means a young bone can easily snap if it catches.Most of the parents the researchers interviewed said they had never given a second thought to the possibility their child might be injured on a slide — and they never would have done so had they known. Parents and caregivers can share these golden playground moments with their kids, but they should leave the sliding to the little ones.