A maternal-fetal monitoring system for use during all stages of pregnancy, including antepartum and intrapartum stages. In a charge pump circuit driven by supply voltage VDD, a maximum of 2VDD or a similar level voltage is applied between the drain and source of a MOSFET, the MOSFET being connected in series with a conduction MOSFET of the same type, the gate of which is supplied with VD-VDD, or a potential which is VDD lower than VD, the drain potential before its connection. Thereafter, a determination is made as to a relative position of a pixel within the image region. As a result, the bearing surfaces may conform to the convex end plates of adjacent vertebra. In the repair process, the solder balls 6 can be restored to an initial condition free of intermetallic compounds.