The value of introducing cerebroplacental ratio (CPR) versus umbilical artery (UA) Doppler alone for the prediction of neonatal small for gestational age (SGA) and short-term adverse outcomes

Objective: To compare the role of umbilical artery (UA) Doppler versus CPR in the prediction of neonatal SGA and short-term adverse neonatal outcome in a high-risk population. Study design: We conducted a prospective study on women referred for fetal growth ultrasounds between 26 and 36 weeks of gestation and with an EFW <20th percentile by Hadlock standard. UA and middle cerebral artery (MCA) Doppler assessments were performed. Abnormal UA Doppler was defined as: pulsatility index (PI) above the 95th percentile and absent or reverse end-diastolic flow. The CPR, calculated as a ratio of the MCA PI by the UA PI, was defined as low if <1.08. The primary outcome was the sensitivity and specificity of the two Doppler assessments to predict neonatal SGA, defined as birthweight <10th percentile by using Alexander curves. The secondary outcomes included umbilical cord arterial pH <7.10, Apgars at 5 minutes <7, NICU admission, respiratory distress syndrome (RDS), hypoglycemia or a composite including any of these secondary outcomes. Chi-square was performed for statistical analysis. Results: Of the 199 women meeting inclusion criteria, 94 (47.2%) had SGA and 68 (34.2%) had a composite adverse outcome. A total of seven pregnancies with FGR had a low CPR. Abnormal UA Doppler showed a better sensitivity for predicting SGA and adverse neonatal outcomes with comparable specificity to low CPR. The area under the ROC curve (AUC) using abnormal UA Doppler for predicting SGA was 0.54, 95% CI 0.50–0.58; and 0.51, 95% CI 0.48–0.53 for low CPR. The AUC for predicting a composite adverse neonatal outcome are: 0.60, 95% CI 0.51–0.68 for abnormal UA Doppler; and 0.54, 95% CI 0.47–0.84 for low CPR. Conclusion: The CPR did not improve our ability to predict neonatal SGA or other short-term adverse outcomes.