If your kids like to moonwalk and jump in those ever-present birthday-party experiences called bounce houses, know about these dangers. A child goes to the ER every 45 seconds because of bouncing injuries.

Researchers at Nationwide Children’s Hospital say inflatable bouncers are the cause of a 15-fold increase in injuries to kids—mostly broken bones, strains and sprains but also head and neck injuries. The findings were published in Pediatrics.

Injury patterns for inflatable bouncers are similar to those the docs see on trampolines, which have national safety guidelines. Bounce houses have no guidelines. So set your own rules.

The researchers suggest parents should consider the risks before allowing their children to use an inflatable bouncer. If you allow your child to use an inflatable bouncer, limit use to children 6 years of age and older. Make sure an adult is there to supervise while the bouncer is in use and allow only one child on the bouncer at a time. If more than one child will be on the bouncer at the same time, the children should be about the same age and size.