OP13.08: Efficiency of cerebroplacental ratio in identifying high‐risk late‐ and post‐term pregnancies

This study aimed to assess the predictive capacity of the cerebro-placental ratio (CPR) for adverse perinatal outcomes in all uncomplicated singleton pregnancies attending a 40-42 weeks appointment. Retrospective cohort study including all consecutive singleton pregnancies undergoing a routine prenatal care appointment after 40 weeks in three maternity units in Spain and the United Kingdom from January 2017 to December 2019. The primary outcome was adverse perinatal outcome defined as stillbirth or neonatal death, Caesarean section or instrumental delivery due to fetal distress during labour, umbilical arterial cord blood pH < 7.0, umbilical venous cord blood pH < 7.1, Apgar score at 5 minutes < 7 and admission to the neonatal unit. Logistic mixed models and ROC curves analyses were used to analyse the data. 3143 pregnancies were analysed, including 537 (17.1%) with an adverse perinatal outcome. Maternal age (Odds Ratio (OR) 1.03 95% Confidence Interval (CI) 1.01 to 1.04), body mass index (OR 1.04 95% CI 1.03 to 1.06), racial origin (OR 2.80 95% CI 1.90 to 4.12), parity (OR 0.36 95% CI 0.29 to 0.45), and labour induction (OR 1.79 95% CI 1.36 to 2.35) were significant predictors for adverse peri-natal outcomes with an area under the ROC curve of 0.743 (95% CI 0.720 to 0.766). The addition of the CPR to the previous model did not improve performance. Additionally, the CPR alone achieved a detection rate of only 11.9% (95% CI 9.3 to 15) when using the 10th centile as the screen-positive cutoff. CPR is a poor predictor of adverse perinatal outcomes in post-term unselected pregnancies. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.