The Natural Response nipple only releases milk when baby is actively sucking. Babies can drink, swallow and breathe in their natural rhythm, just like at the breast. This makes it easier to combine breastfeeding with bottle feeding. The nipple releases milk when the baby actively sucks The Natural Response teat adapts to your baby's natural feeding rhythm, making it easy to combine breastfeeding and bottle feeding. The nipple has a single opening that only releases milk when the baby actively sucks. So, when the baby stops to swallow and breathe, the flow of milk also stops. Natural latch with breast-shaped nipple The wide, soft, flexible nipple is designed to mimic the shape and texture of the breast, helping baby latch on and feed comfortably. Designed to reduce colic and discomfort The anti-colic valve has been designed to reduce the intake of air from the baby's tummy during feeding, helping to reduce colic.