Evaluation of placental function using near infrared spectroscopy during fetal growth restriction

Objectives: To investigate whether a near infrared spectroscopy (NIRS) system is useful for evaluation of the placental function in cases of fetal growth restriction (FGR). Methods: Subjects included 282 delivered neonates of appropriate for gestational age (AGA) and 44 small for gestational age (SGA) babies. The measurement of the concentration of oxyhemoglobin (HbO(2)) and deoxyhemoglobin (HHb) was conducted using transabdominal NIRS targeting the placenta at around 20 weeks, 30 weeks and after 36 weeks of gestation and calculated tissue oxygen indexes (TOI=HbO(2)/total Hb). We correlated between TOIs and causes of FGR. Results: TOIs measured immediately before delivery in the SGA group with severe pre-eclampsia (79.2 +/- 3.8 (%+/- standard deviation (SD); P=0.002)) and placental abnormalities (78.2 +/- 3.6; P=0.043) were higher than in the AGA group (74.0 +/- 4.5). TOIs in the SGA group with umbilical cord abnormalities were lower (69.7 +/- 7.7; P=0.024) than in the AGA group. Conclusion: NIRS might provide information about blood oxygen level of the intervillous space and thus explain the cause of FGR.