Placental pathology in pregnancies with late fetal growth restriction and abnormal cerebroplacental ratio

Introduction: Late fetal growth restriction (FGR) is associated with mild growth restriction and normal or mild abnormal doppler flows. The cerebroplacental ratio (CPR) has been demonstrated as more sensitive to hypoxia than its individual components in these fetuses. We hypothesized that abnormal CPR in late FGR is reflected in specific placental vascular malperfusion lesions. Methods: Retrospective cohort study of late FGR newborns between 2012 and 2022 in a tertiary hospital. Overall, 361 cases were included: 104 with pathological CPR (study group), and 257 with normal doppler flows (control group). The primary outcome was a composite of maternal vascular malperfusion lesions (MVM) and fetal vascular malperfusion lesions (FVM). Secondary outcomes were macroscopic placental characteristics and various obstetrical and neonatal outcomes. Results: The study group had lower birthweight compared with the normal CPR group (2063.5 ± 470.5 vs. 2351.6 ± 387.4 g. P < 0.0001), higher rates of composite adverse neonatal outcomes (34.2% vs. 22.5%, p < 0.0001), lower mean placental weight (318 ± 71.6 vs. 356.6 ± 76.5 g, p < 0.0001), as well as a higher prevalence of Vascular lesions of MVM (15.3% vs. 5.0%, p = 0.002), villous lesions of FVM (37.5% vs. 24.9%, p = 0.02), and composite FVM lesions (36.5% vs. 25.6%, p = 0.04). On multivariate regression analysis for MVM lesions and composite FVM lesions, abnormal CPR was found as an independent risk factor (aOR 2.17, 95% CI 1.63–4.19, and aOR 1.31, 95% CI 1.09–3.97, respectively). Discussions: Abnormal CPR in late FGR is reflected in placental histopathologic vascular malperfusion lesions, and the incidence of these lesions is higher than in FGR placentas with normal CPR.