Fetal neurosonography detects differences in cortical development and corpus callosum in late‐onset small fetuses

OBJECTIVE The aim of this study was to explore whether neurosonography can detect differences in cortical development and corpus callosum length in late-onset small fetuses sub-classified into small-for-gestational age (SGA) or fetal growth restriction (FGR). METHODS A prospective cohort study in 318 singleton pregnancies including 97 normally grown and 221 late-onset small fetuses (birthweight below the 10th centile diagnosed after 32 weeks of gestation). Small fetuses were sub-classified into SGA (birthweight between the 3rd and 9th centile and normal fetoplacental Doppler; n=67) and FGR (birthweight <3rd centile and/or abnormal cerebroplacental ratio and/or uterine artery Doppler; n=154). Neurosonography was performed at 33+/-1 weeks to assess insula, Sylvian fissure, parieto-occipital sulcus depth in the axial views and corpus callosum length in the mid-sagittal plane. Measurements were performed off-line using the Alma Workstation software and adjusted by biparietal diameter or cephalic index. Data analysis was adjusted for confounding factors as gender, gestational age at neurosonography, nulliparity and preeclampsia by linear regression analysis. RESULTS Compared to controls, both SGA and FGR showed significantly thicker insula depth (mm) [control 0.329 (0.312-0.342) vs. SGA 0.339 (0.321-0.347) vs. FGR 0.336 (0.325-0.349), p=0.009]. A linear tendency to reduced Sylvian fissure depth (mm) [control 0.148±0.021 vs. SGA 0.142±0.025 vs. FGR 0.139±0.022, p=0.003] was also observed across the study groups. Corpus callosum length was significantly reduced in FGR cases, while there were no differences between SGA and controls [control 0.500 (0.478-0.531), SGA 0.502 (0.487-0.526) vs. IUGR 0.475 (0.447-0.508), p=0.073 (FGR vs control p=0.02; SGA vs control p= 0,69]. No differences were found in parieto-occipital sulcus depth. CONCLUSION Neurosonography seems to be a sensitive tool to detect subtle structural differences in brain development in late-onset small fetuses. This article is protected by copyright. All rights reserved.