Prediction of neonatal acidosis using the cerebroplacental ratio at different gestational weeks: A case–control study

We evaluated the clinical value of the cerebroplacental ratio (CPR) in predicting neonatal acidosis according to the gestational weeks in late pregnancy. From July 2016 to June 2017, 1018 neonates without acidosis and 218 neonates with acidosis (confirmed postpartum) underwent a prenatal examination and hospital delivery at 28 to 41(+6) weeks in our hospital. The CPR was calculated as the ratio of the prenatal middle cerebral artery-pulsation index (MCA-PI) to the umbilical artery-pulsation index (UA-PI). In neonates without acidosis, the fetal UA-PI decreased with increased gestational age during late pregnancy. Similarly, the MCA-PI decreased with increased gestational age, and decreased significantly during the full pregnancy term. Additionally, the CPR peaked in the middle of the late pregnancy period and then decreased. In contrast, in neonates with acidosis, the prenatal UA-PI increased significantly, MCA-PI declined significantly, and CPR declined significantly in relation to normal values (P < .05). For the prediction of neonatal acidosis, the UA-PI was suitable after 32 weeks and the MCA-PI was suitable before 37 weeks. The cutoff values of the CPR for the prediction of neonatal acidosis at 28 to 31(+6) weeks, 32 to 36(+6) weeks, and 37 to 41(+6) weeks were 1.29, 1.36, and 1.22, respectively. Unlike the UA-PI and MCA-PI, the CPR was suitable as an independent predictor of neonatal acidosis at all late pregnancy weeks. In neonates with acidosis, the z score of the UA-PI increased significantly, whereas the z scores of the MCA-PI and CPR decreased significantly, in relation to normal values (P < .05). The CPR can be used to evaluate the adverse status of fetuses during late pregnancy, providing an early prediction of neonatal acidosis.