I wouldn't think the inseam would be an issue, I just cuff mine if they are too long. If you want them to last any amout of time I wouldn't go smaller than a 14" waist and 15" rise, but thats just me. The newborn fleece pants I have that are made by Carters (not a diaper cover)are a 14" waist, 13" rise and 5" inseam. Hope that helps. Jez