Evaluation of placental oxygenation by near-infrared spectroscopy in relation to ultrasound maturation grade in physiological term pregnancies

A prospective observational study (ClinicalTrial ID: NCT05771415) was conducted to compare placental oxygenation in low-risk, uncomplicated term pregnancies measured by near-infrared spectroscopy (NIRS) in relation to the placental maturity grade determined by ultrasound assessment according to the Grannum scale. We included 34 pregnancies divided into two groups according to placental maturation. For each pregnancy, measurements were taken at the site above the central part of the placenta (test) and at the site outside of the placenta on the lower abdomen (control). Student's t-test was used to compare tissue oxygenation index (TOI) values among the study groups. The normality of distribution was proven by the Kolmogorov-Smirnov test. In women with low placental maturity grade, the mean TOI value above the placenta was 70.38 +/- 3.72, which was lower than the respective value in women with high placental maturity grade (77.99 +/- 3.71; p < 0.001). The TOI values above the placenta and the control site were significantly different in both groups (70.38 +/- 3.72 vs 67.83 +/- 3.21 and 77.99 +/- 3.71 vs 69.41 +/- 3.93; p < 0.001). The results offer a new perspective on placental function based on specific non-invasive real-time oxygenation measurements. Unfortunately, and because of technical limitations, NIRS cannot yet be implemented as a routine clinical tool.