Scientists in the UK have discovered evidence linking brain function variations between the left and right sides of the brain to size at birth and the weight of the placenta:

Tests evaluated blood flow to the brain in response to increased brain activity, exposing differences in the activity of the two sides. Measurements were taken of tiny fluctuations in the temperature of the tympanic membrane in each ear, which indicate blood flow into different parts of the brain.
The researchers found that children who are born small with relatively bigger placentas show more activity on the right side of their brain than their left, a pattern linked to mood disorders, including depression:
"The way we grow before birth is influenced by many things including what our mothers eat during pregnancy and how much stress they are experiencing," says Alexander Jones, an epidemiologist at the University of Southampton, who led the study. "This can have long-lasting implications for our mental and physical health in later life."
These findings have been published online in the journal PLoS One.

via Futurity