Umbilical and fetal middle cerebral artery Doppler at 35–37 weeks' gestation in the prediction of adverse perinatal outcome

Objective To investigate the potential value of cerebroplacental ratio ( CPR ) at 36 weeks' gestation in the prediction of adverse perinatal outcome. Methods This was a screening study in 6178 singleton pregnancies at 35–37 weeks' gestation. Umbilical artery ( UA ) and fetal middle cerebral artery ( MCA ) pulsatility index ( PI ) were measured and the values were converted to multiples of the median ( MoM ) after adjustment from variables in maternal characteristics and medical history that affect the measurements. CPR was calculated by dividing MCA‐PI MoM by UA‐PI MoM . Multivariable logistic regression analysis was used to determine if measuring CPR improved the prediction of adverse perinatal outcome provided by maternal characteristics, medical history and obstetric factors. The detection rate ( DR ) and false‐positive rate ( FPR ) of screening by CPR were estimated for stillbirth, Cesarean section for fetal distress, umbilical arterial cord blood pH ≤ 7.0, umbilical venous cord blood pH  ≤ 7.1, 5‐min Apgar score < 7 and admission to the neonatal unit ( NNU ) and neonatal intensive care unit ( NICU ). Results There was a linear association between CPR and both birth‐weight Z ‐score and arterial or venous umbilical cord blood pH , but the steepness of the regression lines was inversely related to the interval from assessment to delivery. The performance of low CPR  < 5 th percentile in screening for each adverse outcome was poor, with DRs of 6–15% and a FPR of about 6%. In the small subgroup of the population delivering within 2 weeks of assessment, the DRs improved to 14–50%, but with a simultaneous increase in FPR , to about 10%. Conclusion The performance of CPR in routine screening for adverse perinatal outcome at 36 weeks' gestation is poor. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.