Objective: To investigate midbrain growth, including corpus callusum (CC), cerebellar vermis (CV) and cortical development in late fetal growth restriction (FGR) depending on uterine artery (UtA) Pulsatility Index (PI) values.
Methods: This was a prospective study including singleton fetuses with late FGR characterized by abnormal cerebral placental ratio (CPR). According to UtA PI values, the FGR fetuses were subdivided into normal ≤95th centile) and abnormal (>95th centile). Neurosonography was performed at 33-44 weeks of gestations to assess CC and CV lengths and the depth of Sylvian fissure (SF), parieto-occipital (POF) and calcarine fissures (CF). Neurosonographic variables were normalized for fetal head circumference size.
Results: The study cohort included 60 fetuses with late FGR, 39 with normal UtA PI and 21 with abnormal PI values. The latter group showed significant differences in CC (median (interquartile range) normal 35.9 (28.49-45.53) vs abnormal UtA PI 25.31(19.76-35.13) mm; p < 0.0022), CV (normal 25.78 (18.19-29.35) abnormal UtA PI 17.03 (14.07-24.16)mm; p = 0.0067); SF (normal 10.58 (8.99-11.97)vs abnormal UtA PI 7.44 (6.23-8.46) mm; p < 0.0001), POF (normal 6.85 (6.35-8.14) vs abnormal UtA PI 4.82 (3.46-7.75) mm; p < = 0.0184) and CF (normal 04.157 (2.85-5.41) vs abnormal UtA PI 2.33 (2.49-4.01)); p < 0.0382).
Conclusions: Late onset FGR fetuses with abnormal UtA PI showed shorter CC and CV length and delayed cortical development compared to those with normal uterine PI. These findings support the existence of a link between abnormal brain development and changes in utero placental circulation.
Keywords: Fetal growth restriction; cerebellar vermis; corpus callosum; cortical folding; neurosonography; uterine artery PI.