Fetal Magnetoencephalographic Power Spectral Density and Neurobehavioral Correlation in Fetal Growth Restriction (FGR)

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Background Fetal growth restriction (FGR) is associated with adverse neurodevelopmental outcomes, yet reliable prenatal functional biomarkers of altered brain maturation remain limited. Fetal magnetoencephalography (MEG) provides a noninvasive method to assess spontaneous brain activity and may identify early electrophysiological alterations associated with later neurobehavioral outcomes. We evaluated whether fetal MEG power spectral density (PSD) differs between fetuses with FGR and normally growing controls and whether fetal PSD is associated with postnatal neurobehavior. Methods In this prospective observational study, fetuses with FGR (n = 9) and normally growing controls (n = 15) underwent fetal MEG recordings between 28 and 34 weeks’ gestation. Absolute log-transformed PSD was calculated for the delta, theta, alpha, and beta frequency bands. Group comparisons were performed using analysis of covariance with total spectral power as a covariate. Associations between fetal PSD and postnatal neurobehavior, assessed using the NICU Network Neurobehavioral Scale (NNNS), were evaluated using partial correlation analyses controlling for total spectral power. Results No significant group differences were observed in the delta or theta frequency bands. Alpha power was significantly lower in the FGR group than in controls (difference = 1.10 dB; p = 0.013), while beta power demonstrated a larger, but nonsignificant decrease (difference = 1.59 dB; p = 0.061). Exploratory analyses demonstrated moderate-to-large associations between fetal spectral power and several NNNS domains. Greater delta power and lower alpha and beta power were associated with less favorable neurobehavioral performance, particularly in domains related to regulation, tone, and attention. Conclusions Fetal MEG identified subtle alterations in spontaneous brain activity associated with fetal growth restriction and demonstrated associations between prenatal electrophysiological measures and early postnatal neurobehavior. Although these findings require confirmation in larger prospective studies, they support further investigation of fetal MEG as a potential biomarker of early neurodevelopmental vulnerability.