A breastpump unit for expressing human breastmilk has a breastshield for placing on a human mother's breast, a vacuum pump for generating an underpressure, and a suction line for connecting the breastshield to the vacuum pump and for transferring to the breastshield the underpressure generated by the vacuum pump. The breastpump unit also has a pressure sensor. In addition, a measuring line is present, wherein the measuring line extends from the breastshield to the pressure sensor.