With the Philips AVENT Classic+ nipple, your baby controls milk flow, which can help reduce overeating and spit-up. The unique valve flexes to allow air into the bottle, promoting healthy, active feeding and reducing fussing and colic.Unique valve on the nipple flexes to your baby's feeding rhythm. Milk will only flow at the pace chosen by your baby to minimize overeating and spit-up, burping and gas.Sleep and nutrition are vital to your baby's health and happiness. A randomized clinical trial was carried out to see whether infant baby bottle design affects "infant behavior". The Philips AVENT Classic baby bottle was shown to significantly reduce fussing by approximately 28 minutes a day as compared to the comparator bottle (46 min vs 74 min, p=0.05) This was especially true during the night-time.