Deep learning assessment of fetal brain maturation on 3D ultrasound volumes in early-onset fetal growth restriction.

objectivesTo quantify fetal brain maturation in fetuses with early-onset fetal growth restriction (FGR) by estimating gestational age (GA) based on the appearance of gyrification and individual brain structures from three-dimensional (3D) ultrasound volumes using a deep-learning model trained on optimally developing subjects. The association of altered fetal brain maturation, as a potential marker of cumulative intrauterine stress, with an increased risk of neonatal complications was also explored.

methodsThis was a prospective, observational, single-center cohort study of singleton pregnancies with early-onset FGR conducted at the University Medical Center Utrecht between June 2022 and June 2024. Early-onset FGR was defined as an estimated fetal weight (EFW) and/or abdominal circumference below the 10

resultsThe study included 43 growth-restricted fetuses with high-quality 3D ultrasound scans (13 of which had brain-sparing FGR) at a median GA of 27.1 (interquartile range (IQR), 26.1-27.7) weeks. The estimated GA was significantly lower than the actual GA in early-onset FGR, with ΔGA of -4.6 (IQR, -9.8 to -1.0) days based on the whole scan, ΔGA of -4.9 (IQR, -9.0 to -1.2) days based on the SF, ΔGA of -5.4 (IQR, -7.4 to -1.7) days based on the POF and CLC, and ΔGA of -3.2 (IQR, -6.8 to 0.3) days based on the CB (P < 0001 for all). There was no significant difference in brain maturation between fetuses with brain-sparing and those with non-brain-sparing FGR or between male and female fetuses. The EFW percentile correlated significantly with the degree of delayed maturation (whole-scan data, r = 0.377; P = 0.013) and contributed to our multivariable model. Socioeconomic status, fetal sex and CPR were not associated with the delay in maturation. Seventeen neonates were born < 32.0 weeks' gestation and admitted to the neonatal intensive care unit. The ΔGA was higher in the neonates with perinatal complications, indicating greater delay in brain maturation.

conclusionsDelayed fetal brain maturation in early-onset FGR has been demonstrated using a 3D ultrasound deep-learning model. These findings highlight the potential role of 3D ultrasound in the assessment of fetal brain maturation and support the need for continued research into these findings and their long-term neurodevelopmental consequences in early-onset FGR. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.