An electronically controlled breast pump for generating cyclical suction includes a cumulative vacuum pump and a plurality of switches including at least an expression mode cycle time selection switch, a peak vacuum level selection switch, and a stimulation mode switch. A controller coupled to the cumulative vacuum pump controls the apparatus which optionally further includes a four-layer assembly of the various features, an adjustable safety valve, and/or a pump head with a groove traversing top dead center of the pump head.
