The esCCO monitor uses non-invasive blood pressure (NIBP), three-lead ECG and pulse oximetry (SpO2). These modalities are part of routine clinical monitoring, which makes this monitor ideal for measuring CO in the normal pregnant population. Patients admitted to the labour ward often require monitoring with at least NIBP and SpO2, hence only the three-lead ECG is 'extra'. By validating this monitor, CO measurement across a variety of clinical scenarios in the pregnant population will be possible.