Reduced gyrification in fetal growth restriction with prenatal magnetic resonance images

Placental-related fetal growth restriction, resulting from placental dysfunction, impacts 3-5% of pregnancies and is linked to elevated risk of adverse neurodevelopmental outcomes. In response, the fetus employs a mechanism known as brain-sparing, redirecting blood flow to the cerebral circuit, for adequate supply to the brain. In this study we aimed to quantitatively evaluate disparities in gyrification and brain volumes among fetal growth restriction, small for gestational age and appropriate-for gestational-age fetuses. Additionally, we compared fetal growth restriction fetuses with and without brain-sparing. The study encompassed 106 fetuses: 35 fetal growth restriction (14 with and 21 without brain-sparing), 8 small for gestational age, and 63 appropriate for gestational age. Gyrification, supratentorial, and infratentorial brain volumes were automatically computed from T₂-weighted magnetic resonance images, following semi-automatic brain segmentation. Fetal growth restriction fetuses exhibited significantly reduced gyrification and brain volumes compared to appropriate for gestational age (P < 0.001). Small for gestational age fetuses displayed significantly reduced gyrification (P = 0.038) and smaller supratentorial volume (P < 0.001) compared to appropriate for gestational age. Moreover, fetal growth restriction fetuses with BS demonstrated reduced gyrification compared to those without BS (P = 0.04), with no significant differences observed in brain volumes. These findings demonstrate that brain development is affected in fetuses with fetal growth restriction, more severely than in small for gestational age, and support the concept that vasodilatation of the fetal middle cerebral artery reflects more severe hypoxemia, affecting brain development.