Cocoons are popular for photography sessions right now, but they're also very practical, particularly in the NICU. Because preemies are, in fact, premature they have a multitude of special developmental needs. One is for swaddling. It makes sense. By "age" they should still be in the ultimate swaddling environment but for whichever of many possible reasons they've been brought out into the world where it's not dark, warm, wet, and tightly encompassing for their fetal development, so we make up for it where we can. Preemies, the younger the more so, are most comforted by what their senses/developing bodies need: lack of stimulation and lots of physical boundaries, namely being squished up like a ball and boxed in. Okay, that was a joke, but, in essence it's true. They are happiest with their little arms arms and legs folded in mid-line to their bodies with their hands at their faces, and a snug swaddle of blanket giving them a simulated uterus of sorts. Cocoons work great for this.
In the NICU, the little Littles are snug in their isolettes, or "cages" as my niece Kaylee once called them sort of funnily appropriately, with plenty of warmth and snugglers or Z-flows to position them, but a great use for cocoons/cuddles/sacks would be during the time when parents get to hold their babies, for example, each day when their bed linens are being changed and cleaned.
Another great use is for photographs, like all babies. Just because our babies are in the unit instead of home doesn't mean they don't still get tons of pics taken or don't get to celebrate their first holidays. Orange cocoons with matching pumpkin hats for fall, Red/Green sets for Christmas, pastels for Easter, are all Kodak moments in the waiting.
From ReliefShare.org for this cocoon pattern, along with other great free knitting patterns.
"The general sizes are:
XXS – 14″ long x 50 stitches wide (6″ across) – 12″ diameter
XS – 16″ long x 60 stitches wide (8″ across)
S – 18″ long x 70 stitches wide (10″ across)
M – 20″ long x 80 stitches wide (10″ across)
L – 23″ long x 80 stitches wide (12″ across)
XL – 25″ long x 80 stitches wide (12″ across)
The hospitals use the XS size the most, the the families we donate to use the S, M and L the most as well as the XL. The XXS are used by the hospital, some of them for infant demise." --Relief Share
Keep a couple of important things in mind for all babies, namely current SIDS reccomendations. I personally knit shorter rather than longer when it comes to cocoons. Through personal experience, I (we in the NICU) have found that the 14 inch size fits 3.5-5 lb-er little Littles from their bent knees to just under their chins which is perfect. Per SIDS recommendations, you do not want to add a hood, any kind of fold over flap at the top, or a length so long that it might accidentally cover the baby's face. A handy reference for neck to toe infant measurements can be found here (Bev's Country Cottage). My point is that I would knock a couple of inches off the length of each of these dimensions.
Check out Relief Share, an organization in Houston Missouri and Boise Idaho, founded by Carol Green to help as many in need as possible, from individuals to organizations such as hospitals and clinics, nursing homes, nursery schools, shelters, and other relief organizations. They're doing great work over there, so please donate if you can, whether it's in the form of money, yarn, material, completed projects, etc. Needed items and donation links can be found at Relief Share Current Projects.
Another great pattern from Relief Share is the Preemie Newborn Knitting Gown with sleeves, which to be honest, is even better for the NICU because it has sleeves that make the top comply automatically to SIDS recommendations and the drawstring bottom will make the RN's add your name and "hallelujah" to the same sentence for ease of diaper changes!