A breast pump (100) is provided comprising a vacuum pump (120) which is configured to be operated at different vacuum profile settings, a controller (140) configured to control an operation of the vacuum pump (120) based on the different vacuum profile settings, and a breast fullness estimator (150) configured to estimate a fullness of a breast based on a duration of a milk expression session. The controller (140) is configured to select a vacuum profile setting based on the breast fullness estimation of the breast fullness estimator (150). Hence, the efficiency of the breast pump is increased as the operation of the vacuum pump is adapted to the estimated breast fullness.