Impact of Intrauterine Growth Restriction on Fetal Cortical Brain Development: A Neurosonographic Assessment at 28-36...

Cortical folding during fetal brain development reflects neural maturation. Fetal growth restriction (FGR) may disrupt this process, potentially affecting neurodevelopmental outcomes. Although ultrasound enables noninvasive sulcal assessment, so normative data and objective tools are lacking. The purpose of the current study was to assess the impact of FGR on fetal cortical development using neurosonography and establish a third-trimester nomogram for cortical maturation.

This prospective study included 425 singleton pregnancies (330 appropriate-for-gestational-age [AGA], 54 symmetrical FGR, and 41 asymmetrical FGR) at 28-36 weeks. Conducted at a Tehran tertiary center (2023-2024), the study included cases with normal anatomy and negative aneuploidy screening. Neurosonographic parameters including Sylvian fissure (SF), insula, parieto-occipital fissure (POF), cavum septum pellucidum (CSP) width, and ventricular diameter were measured and the ratios calculated relative to biparietal diameter (BPD). ANOVA and post-hoc tests were applied and statistical significance was set at p<0.05.

No significant differences in neurosonographic ratios (e.g., SF/Insula, POF/BPD, CSPW/BPD) were found between AGA and FGR groups. However, unadjusted SF and insular depths were reduced in symmetrical FGR fetuses with head circumference (HC) <10th percentile. Asymmetrical FGR showed no differences. A gestational-age-based nomogram was developed for AGA fetuses.

While absolute sulcal measurements vary with head size in FGR, biometric adjustments (e.g., BPD ratios) improve cortical maturation assessment. The study supports ratio-based neurosonography and provides normative data for objective fetal brain evaluation.