As with any items made for an organization, I would suggest that you check with them first for their particular requirements. I have made isolette covers for my local hospital NICU and here are their requirements:
*Washable materials: cotton, flannel or fleece
*Bottom Layer - a dark fabric that is black or navy
*Top Layer- any baby friendly pattern & color
*Quilted thick enough to block light
*Size - 40 X 50 inches or 50 X 60 inches (Yes that seems large but it must completely cover the isolette to block out light.)
*Durable to last through hospital laundering
**No tied quilts
**No tied (no sew) fleece blankets
**Do not embellish with ribbons, button etc.
I also suggest checking to see it their is a need for additional quilts. I checked a couple of weeks ago and my local NICU did not need any additional isolette covers. (My assumption is that a local guild or group has made a number of covers and the need is met currently.)