Parents of newborns like to keep their babies close using what’s known as body-worn baby carriers, but a new study coming out of Boise State’s Babi Lab says not all of those carriers are created equal and some may have troubling effects on your baby’s hips.

Erin Mannen is an Assistant Professor of Mechanical and Biomedical Engineering at Boise State University and she’s the Director of the Boise Applied Biomechanics of Infants Lab, which conducted the new study.