Predictive role of Doppler indices of cerebral–placental–uterine ratio and umbilico-cerebral ratio for late-onset fetal growth restriction: a prospective cohort study

Abstract

Predicting late-onset foetal growth restriction (FGR) has proven to be rather challenging. In this study, we propose a new parameter, cerebral–placental–uterine (CPU) ratio and umbilico-cerebral (UC) ratio for this matter. Results of this study which included a total of 227 nulliparous women showed that an increase in CPU ratio (OR = 0.45; 95% CI: 0.23–0.88; p=.020) was associated with lower odds of foetal weight above the 10th percentile at birth. CPU ratio measured at 35–37 weeks of gestation had an AUC of 0.78 (95% CI: 0.58, 0.98), sensitivity of 0.62 (95% CI: 0.24, 0.91) and specificity of 0.90 (95% CI: 0.79, 0.96) for prediction of late-onset FGR, which showed higher accuracy than UC ratio. As some cases of the late-onset FGR are not diagnosed by foetal biometry, it is important to find Doppler parameters that can help us predict these cases and CPU ratio may help physicians in detection of high-risk foetuses that will benefit from earlier intervention. Impact Statement What is already known on this subject? Late-onset foetal growth restriction (FGR) defined by an FGR diagnosis after 32 weeks of gestational age, can lead to short- and long-term morbidities and early diagnosis is the key to prevent these complications. What do the results of this study add? Results showed that each unit increase in numeric variables including CP ratio (OR = 0.29, p=.006), and CPU ratio (OR = 0.40, p=.006) was associated with lower odds of the foetal weight above the 10th percentile in the second ultrasound at 35–37 weeks. In other words, CPU ratio can prove to be useful marker in prediction of late-onset FGR. What are the implications of these findings for clinical practice and/or further research? Our prospective cohort study confirms the added value of low CPU ratio, with higher predictive accuracy than UC ratio, in predicting late-onset FGR. Detection of late FGR remains poor, but it is important to prevent stillbirth so further studies on the role of CPU ratio in predicting FGR and perinatal outcomes are needed.