Fetal Brain Biometry and Long-term Neurodevelopmental Outcome

Purpose: Controversial cut-offs for diagnosis of microcephaly and macrocephaly lead to uncertainty regarding long-term prognosis. We assessed the agreement between the clinically used modalities for measuring fetal brain, and the head circumference at birth. We explored the correlation to long-term neurodevelopmental outcome.

Methods: Prospective study conducted between 2011-2019 at a tertiary referral medical center. Microcephaly and macrocephaly were defined as -2 SD and 2SD, respectively. Sonographic head circumference (HC), 2D MRI bi-parietal diameter (BPD) and occipito-frontal diameter (OFD), 3D MRI supra-tentorial volume (STV), and head circumference (HC) at birth were measured and converted into centiles according to gestational age. Spearman`s rank correlation coefficient was used to assess the correlation between the modalities. Neurodevelopmental outcome was evaluated using Vineland II adaptive behavior scales between the ages 2 and 6 years old.

Results: A total of 88 fetuses were included. Mean gestational age at the time of fetal US and brain MRI acquisition were 34.4 ± 2.8 and 34.6 ± 2.6 weeks, respectively. Sonographic HC, OFD on 2D MRI, and STV on 3D MRI were all found to be correlated with the HC at birth (Rs= 0.865, p<0.001; Rs 0.816, p<0.001; Rs= 0.825, p < 0.001, respectively). No significant correlation was found between Vineland scores and the supratentorial brain volume (STV).

Conclusions: There is a statistically significant agreement among the different prenatal clinically used modalities for measuring fetal brain and the HC at birth. When isolated, there is no difference in the long-term neurodevelopmental outcomes in microcephalic and macrocephalic fetuses.