Parents have come to rely on the award-winning Dr. Brown's Natural Flow Bottle because of the health benefits for baby. The Dr. Brown's Natural Flow Bottle features a patented internal vent system that creates positive-pressure feeding and prevents vacuum and air bubbles, thus reducing digestive problems including colic, spit-up, burping and gas. The BPA-free polypropylene Dr. Brown's Natural Flow Bottle also preserves vitamins and lipids better than standard bottles and reduces fluid build-up in baby's tender ears. The Dr. Brown's Natural Flow Bottle is for newborns and up.