The invention proposes a device (1) and a corresponding method, wherein the device (1) comprises: a first element (10) to be attached to a breast of a breastfeeding mother and a first marker (11) located on the outer surface (100) of the first element (10), wherein the first marker (11) is used for indicating a position of a mothers breast that the babys lip is expected to contact in order to correctly hold the mothers breast. With the device (1) attached to the mothers breast, the first marker (11) indicates a position that the babys lip is expected to contact, and the breastfeeding mother can have a clear view of whether the baby correctly holds the mothers breast according to the distance between the first marker (11) and the babys lip.