Role of cerebroplacental ratio for fetal assessment in prolonged pregnancy

Objective The aim of this study was to assess the role of the cerebroplacental ratio ( CPR ), i.e. the ratio between the middle cerebral artery and umbilical artery pulsatility indices, in detecting fetal compromise in prolonged pregnancy. Methods Women attending a dedicated postdates clinic at 41 weeks' gestation were recruited for the study and CPR was calculated at 41+3 weeks. Induction of labor was offered at 42 weeks to those women still undelivered. Unfavorable outcome was defined as cord arterial pH < 7.15 with a base deficit of > 11  mM /L or operative delivery for abnormal intrapartum fetal electrocardiogram ST ‐segment analysis. The 5 th centiles of the CPR , obtained from published reference ranges (0.90) and from our population (0.98), were used as lower cut‐off values. Results Three hundred and twenty women who reached a gestational age of over 41 weeks were eligible for inclusion in the study. The median gestational age at delivery was 294 (range, 289–300) days. Unfavorable outcome was observed in 58/320 pregnancies. There was no significant difference in the proportion of unfavorable outcomes between the two groups defined using either CPR cut‐off value (both P > 0.05). Conclusion CPR is not predictive of unfavorable outcome in women with pregnancies lasting more than 41 weeks. Copyright © 2012 ISUOG. Published by John Wiley & Sons Ltd.