# Normative growth trajectories of fetal brain regions validated by satisfactory maturation of neurodevelopmental domains at 2 years of age

## TL;DR

This study uses deep learning to map fetal brain growth patterns and shows that brain development is similar across diverse populations when environmental factors are minimal.

## Contribution

The study introduces a fetal brain maturation index and 28 normative growth trajectories validated by neurodevelopmental outcomes at 2 years.

## Key findings

- 28 region-specific normative growth trajectories were defined for fetal brain structures.
- A fetal brain maturation index was introduced to quantify biological age and deviations.
- Between-site variance was low, indicating similar brain development across populations with minimal environmental constraints.

## Abstract

We previously constructed a qualitative, 3D ultrasound derived atlas of the normative spatiotemporal dynamics of fetal brain maturation. Here, using the same healthy multi-national cohort, we applied deep learning methods to 4205 fetal brain scans from 18–27 weeks’ gestation, to produce an extensive, quantitative description of the growth of 16 fetal brain structures associated with satisfactory domain-specific neurodevelopmental scores at 2 years of age. The methodology, which is publicly available, takes less than 10 seconds per scan. We define 28 region-specific, functionally relevant, normative growth trajectories, a ratio between the relative volumes of the insular (rILV) and parietal (rPLV) lobes reflecting asynchronous maturation of fetal brain regions, and introduce a fetal brain maturation index that quantifies biological age and deviations from chronological age. Finally, the very low percentage of variance explained by between site differences (0.6% to 5.8% of the total variance) reinforces a fundamental biological principle: fetal growth and development across populations with diverse ancestries is similar provided that environmental constraints on growth are minimal.

This study mapped normative growth trajectories of 28 fetal brain phenotypes derived from 4,205 3D ultrasound scans collected across 7 international sites. The low variance between sites reinforces the principle that the brain develops similarly when environmental constraints are minimal.