Short Sleeved Onesie
You'll want about six of these. One spare for the diaper bag, one spare for the car (for when you forget the diaper bag) and four for the house, so it's ok if you skip a day of laundry. See full First Essentials Shopping List
Both the American Consumer Product Safety Commission and Health Canada give manufacturers of children’s apparel a choice: Clothing may be treated with chemical flame retardants or be classified as 100% cotton and snug fitting.