An apparatus (10) for measuring one or more labor progress parameters (25) as the dilation of the endocervical canal (8), the rotation and the position of the head (4) of the foetus (3) during the descent, the duration and the intensity of the uterine contractions, other morphological and physiological parameters, without introducing foreign objects into the body of a pregnant woman (2) and independently from the sensitivity of the operator. The apparatus (10) comprises automatic means for tracking, in a sequence of ultrasound images (11,12) that are obtained by an ultrasound probe (1), one or more regions of interest (ROI, 21), that may be both two-dimensional or three-dimensional and are centered about anatomic reference points (28) that define said parameters selected in a reference image by a displaying unit (14). The tracking means comprises: a) a means for calculating a function (f) at the pixels of the ROI of the reference image and of images preferably sampled among the images of the sequence, b) a means for calculating iteratively at the positions of the ROI in subsequent images, by a means of comparison between the values of the function (f) calculated in the pixels of the ROI of a current image and the values of the function (f) calculated in the pixels of the ROI of a subsequent ultrasound image c) a means for comparing each position of the ROI with the position of the ROI in the reference image and for calculating the labor progress parameter responsive to said comparison. The new position of the region of interest may be defined as a domain in which a predetermined object function assumes a minimum value.
