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.