Fabric made from Bamboo is one of the softest * Bamboo - the softest, all natural, Green Fiber around. * Doctor recommended for postpartum. See Product Description below. * Sizing: Measure the circumference of your belly just prior to delivery, and subtract 3-5 inches. XS: 28-32". SM: 33-37". MED: 38-43". LG: 44-49". * If you are purchasing after birth, choose based on your current waist size