Supplementary Material for: Comparison between Cerebroplacental Ratio and Umbilicocerebral Ratio in Predicting Adverse Perinatal Outcome in Pregnancies Complicated by Late Fetal Growth Restriction: A Multicenter, Retrospective Study

<b><i>Introduction:</i></b> The role of cerebroplacental ratio (CPR) or umbilicocerebral ratio (UCR) to predict adverse intrapartum and perinatal outcomes in pregnancies complicated by late fetal growth restriction (FGR) remains controversial. <b><i>Methods:</i></b> This was a multicenter, retrospective cohort study involving 5 referral centers in Italy and Spain, including singleton pregnancies complicated by late FGR, as defined by Delphi consensus criteria, with a scan 1 week prior to delivery. The primary objective was to compare the diagnostic accuracy of the CPR and UCR for the prediction of a composite adverse outcome, defined as the presence of either an adverse intrapartum outcome (need for operative delivery/cesarean section for suspected fetal distress) or an adverse perinatal outcome (intrauterine death, Apgar score &lt;7 at 5 min, arterial pH &lt;7.1, base excess of &gt;−11 mEq/mL, or neonatal intensive care unit admission). <b><i>Results:</i></b> Median CPR absolute values (1.11 vs. 1.22, <i>p</i> = 0.018) and centiles (3 vs. 4, <i>p</i> = 0.028) were lower in pregnancies with a composite adverse outcome than in those without it. Median UCR absolute values (0.89 vs. 0.82, <i>p</i> = 0.018) and centiles (97 vs. 96, <i>p</i> = 0.028) were higher. However, the area under the curve, 95% confidence interval for predicting the composite adverse outcome showed a poor predictive value: 0.580 (0.512–0.646) for the raw absolute values of CPR and UCR, and 0.575 (0.507–0.642) for CPR and UCR centiles adjusted for gestational age. The use of dichotomized values (CPR &lt;1, UCR &gt;1 or CPR &lt;5th centile, UCR &gt;95th centile) did not improve the diagnostic accuracy. <b><i>Conclusion:</i></b> The CPR and UCR measured in the week prior delivery are of low predictive value to assess adverse intrapartum and perinatal outcomes in pregnancies with late FGR.