an intrauterine pulse oximetry apparatus and method are provided to measure fetal blood oxygen saturation at sites in a preferred region on the fetus . the sensor of the apparatus is attached to a stiff cable which can be inserted into the uterus past the presenting part and transcervical region of the fetus . the cable may have visual and tactile markings by which the user , without seeing or feeling the sensor , can guide it to an appropriate site on the fetus .