A closure assembly (11) for a babys bottle (10) comprising a regulatorcap (16) which is adapted to be mounted to the bottle (10) and having one or moreapertures (22), a teat collar (17) threaded to the bottle and moveable betweenan open and closed position and a teat (18) coupled to the teat collar (17) and havingan outlet (45) for passage of fluid, the teat having (17) a base flange (38) adaptedfor cooperation with the regulator cap (16) such that in the open position of saidteat collar (17) fluid can pass through the one or more apertures (22) and throughthe teat outlet (45) and air can pass between the base flange (38) and regulatorcap (16) into the bottle (10) through one or more of the apertures (22). In the closedposition, fluid is prevented from passage through the one or more apertures (22)into the teat (16) and air is prevented from passing between the base flange (38)and regulator cap (16) into the bottle (10).
