Breast pump comprising a breast shield arrangement having: a breast shield for receiving a user's breast therein, and a photoplethysmographic, PPC, sensor for transmitting an input signal into the breast and receiving a corresponding reception signal in response, said reception signal comprising AC and DC components, the DC component of the reception signal comprising information on the change of bulk absorption in the breast indicating changes in milk flow in the breast, the breast pump further comprising - a pressure source in air-ducting connection to the breast shield for generating increased or reduced pressure in the breast shield to extract breast milk, and - a control unit adapted to control the pressure source on the basis of the DC component of the reception signal comprising information on the change of bulk absorption in the breast, and - a signal processing unit for analysing AC and DC components of said reception signal, wherein the signal processing unit is configured to evaluate the DC component of the reception signal comprising information on the change of bulk absorption in the breast, in particular on the increase of fluid due to the start of milk flow in the breast, and generate an according feedback signal for adjustment of the function of the pressure source by the control unit. a breast shield for receiving a user's breast therein, and a photoplethysmographic, PPC, sensor for transmitting an input signal into the breast and receiving a corresponding reception signal in response, said reception signal comprising AC and DC components, the DC component of the reception signal comprising information on the change of bulk absorption in the breast indicating changes in milk flow in the breast, the breast pump further comprising - a pressure source in air-ducting connection to the breast shield for generating increased or reduced pressure in the breast shield to extract breast milk, and - a control unit adapted to control the pressure source on the basis of the DC component of the reception signal comprising information on the change of bulk absorption in the breast, and - a signal processing unit for analysing AC and DC components of said reception signal, wherein the signal processing unit is configured to evaluate the DC component of the reception signal comprising information on the change of bulk absorption in the breast, in particular on the increase of fluid due to the start of milk flow in the breast, and generate an according feedback signal for adjustment of the function of the pressure source by the control unit. - a pressure source in air-ducting connection to the breast shield for generating increased or reduced pressure in the breast shield to extract breast milk, and - a control unit adapted to control the pressure source on the basis of the DC component of the reception signal comprising information on the change of bulk absorption in the breast, and - a signal processing unit for analysing AC and DC components of said reception signal, wherein the signal processing unit is configured to evaluate the DC component of the reception signal comprising information on the change of bulk absorption in the breast, in particular on the increase of fluid due to the start of milk flow in the breast, and generate an according feedback signal for adjustment of the function of the pressure source by the control unit.