Combined CW and FMCW near infrared spectroscopy for transabdominal fetal oximetry

We propose a new non-invasive approach to transabdominally measure fetal oxygen saturation based on time-domain interferometric near-infrared spectroscopy. We use the frequency-modulated continuous-wave technique to measure the time resolved reflectance of near-infrared light shining on the maternal abdomen. By modeling the maternal abdomen as two-layered media (i.e. maternal and fetal tissue) through diffusion equations, the optical properties of both the maternal and fetal tissue can be deduced. Using two optical wavelengths, oxygen saturation can be measured for both the mother and fetus. This technique could provide an important assessment of intrapartum fetal health during labor in the delivery room.