Introduction

Fetal growth restriction (FGR) is when pathological constraints limit fetus growth. By definition, FGR decreases fetus body mass to <10th percentile. Due to limited growing conditions, growth-restricted fetuses tend to have decreased brain volume, decreased number of cells, and abnormal body structures and functions. However, to secure essential life functions, growth-restricted fetuses tend to direct blood flow and concentrate metabolism into the brain (and decrease metabolism in other body parts), and this is known as the brain-sparing effect. Thus, growth-restricted fetuses usually have relatively large brains compared to body size. Having increased brain metabolism, which produces reactive oxygen species and causes neuron damage, it is likely that the brain-sparing effect would increase REM sleep (in which neuron repair takes place) in growth-restricted fetuses.

Methodology

The project has a modular two-part design, focussing on two potential major questions. Firstly, the project would quantitatively investigate how brain-sparing affects brain-to-body size scaling. Even though fetal growth results in decreased fetus weight and overall brain size, as most blood flow is directed to the brain, the brain-sparing effect results in increased brain size relative to the body. In this project, we would use the allometric equation to mathematically define the scaling relationship between brain and body size after the brain-sparing effect. Secondly, the project would investigate the side effects of brain-sparing on sleep time and cognitive scores. Since decreased body mass would increase metabolism per unit mass and increase cell damage made by metabolic processes, theoretically, growth-restricted fetuses require more REM sleep time for cell repair. To investigate this hypothesis, we would measure REM sleep time using brain wave recordings and analyse the actual effects on cognitive function using cognitive scores.

Significance

This project relates to the third UN Sustainable Development Goal, Good Health and Well-being, in that by understanding how fetuses decrease metabolism to increase survival rate when encountering constraints and investigating its side effects, we might be able to enhance the mechanisms artificially and minimize the side effects.