A breastpump assembly is disclosed. The breastpump assembly includes a breast shield within which a woman's breast is received, a conduit structure communicating with the breast shield, a container for collecting milk, and a valve mechanism closing the breastpump assembly from ambient air when initially provided to a user, the valve mechanism being opened to allow ambient air to pass into the breastpump assembly through removal of the container, so as to substantially disable the breastpump.