Medium Flow Nipple is ideal for babies 3 months 

The soft, naturally shaped AVENT nipple makes it easier to switch between breast and bottle feeding, and promotes healthier, active feeding. The built-in valve flexes with baby's natural feeding rhythm and lets baby control the flow of milk, which can help reduce overeating and spit-up. The valve also prevents a vacuum and pushes bubbles out of the milk, for less air in baby's tummy. This reduces colic and gas after feeding.