Inner and outer shield parts of a breastshield are joined to form an enclosure defining a pressurizable chamber. The inner shield part has at least a portion thereof movable relative to the outer shield part when the chamber is subject to a negative or a positive pressure. A first pressure port is in communication respectively with the chamber for connection with a fluid pressure source of a first pressure. A second pressure port is in communication with the interior for connection with a pressure source of a second pressure. The breastshield is thus capable of being subjected to two different pressures, such as a positive pressure to move (expand) the chamber into the interior, so as to compress or massage the nipple/breast, and a negative pressure in the interior to draw the nipple/breast further therein for the expression of milk. The pressures can be independently controlled, and may furthermore alternate being negative and positive through the same pressure port. In one embodiment, an enclosure defines first and second chambers. The chambers are separate from each other and independently pressurizable. A greater plurality of chambers is furthermore contemplated. The invention takes the form of a variety of different embodiments of breastshields and breastpumps for breastmilk pumping having sundry novel attributes and advantages.