Abstract: The present invention relates to a device for monitoring a concentration of an analyte in a foetus. The device comprises a biosensor for electrochemically measuring a concentration of an analyte in the foetus, a protrusion configured to be at least partially inserted into foetal tissue, and a device body supporting the biosensor and the protrusion. The device is configured such that when the device body contacts the surface area of the foetal tissue, the device body can be anchored to the foetal tissue and the protrusion can be inserted into the tissue so that the reactive substance of the biosensor electrochemically reacts with the analyte in the foetal tissue and in response to the electrochemical reaction the electrode of the biosensor detects an electronic signal, a strength of the electronic signal being indicative of the concentration of the analyte.