Apparatus and methods for a baby bottle assembly are provided. The baby bottle assembly may include a nipple and an internally threaded collar configured to receive a bottom portion of the nipple. The assembly may also include a receptacle including an externally threaded neck and a cylindrical surface defining a mouth of the receptacle. The assembly may further include a bottle insert including a flange, the flange having an outer circumference greater than or equal to a circumference of the mouth. A top surface of the bottle insert may include a plurality of apertures and a top portion of a hollow protrusion. A bottom surface of the bottle insert may include a bottom portion of the hollow protrusion, the plurality of apertures and a diaphragm.
