BabyCO Handheld carbon monoxide monitors Measuring breath carbon monoxide is an established technique used in smoking cessation. The BabyCO is a powerful diagnostic tool for measuring alveolar Carbon Monoxide in PPM concentrations. This is measured simply from the mother's expired breath. From this measurement the amount of Carbon Monoxide in the foetus is derived and is represented as foetal Carboxyhemoglobin (%FCOHB). The mother's CO concentration in PPM will then be displayed, along with the foetal %COHB.