My grandson just got home from St. John's NICU in Springfield. When my son first went into the unit, he was quite surprised to find a quilt draped over the top of the Isolette--thought I'd already been there! I believe that's how they use the quilts in that facility. 30-35" square will work. Would be good to have a back with interest in that situation. I didn't see any quilts used over the babies in bed but they were wrapped when being held. They did use fleece blankets for that. --and they were given the ones their baby used while there.