The system determines a fetal blood oxygenation level by activating two or more light sources, having different wavelengths, which are positioned on the maternal abdomen of a pregnant mammal to direct light into a maternal abdomen toward a fetus. The system then receives a maternal signal from a first photodetector, which is positioned on the maternal abdomen to receive reflected light that traverses maternal tissue. The system also receives a mixed signal from a second photodetector, which is positioned on the maternal abdomen to receive reflected light that traverses both maternal and fetal tissue. The system performs a filtering operation that removes maternal signal components from the mixed signal to produce a fetal signal. The system determines the fetal blood oxygenation level by performing a pulse-oximetry computation on the fetal signal. The system dynamically adjusts operational parameters in the face of changing variables, such as fetus position and depth.