A child's brains grows most rapidly just after birth and reaches half its adult size within three months, according to scientists from the University of California.
Using advanced scanning techniques, researchers also found that male brains grew more quickly than those of female infants with areas involved in movement developing at the fastest pace and memory growing slowest.
For centuries doctors have estimated brain growth using measuring tape to chart a baby's head circumference over time but as head shapes vary, these tape measurements are not always accurate.
Study lead Dr Dominic Holland believes recording the normal growth trajectory of individual parts of the brain through new scanning techniqes can help health professionals better understand how early disorders arise including developmental conditions like autism.
"A better understanding of when and how neurodevelopmental disorders arise in the postnatal period may help assist in therapeutic development," said the neuroscience expert from UC San Diego School of Medicine.
"Being able to quantify related changes in structure size would likely facilitate monitoring response to therapeutic intervention. Early intervention during a period of high neuroplasticity could mitigate the severity of the disorders in later years."
To derive the findings Dr Holland's team scanned the brains of 87 healthy babies from birth to three months. They saw the most rapid changes immediately after birth - newborn brains grew at an average rate of 1% a day. This slowed to 0.4% per day at the end of the 90-day period.
They found the cerebellum, an area of the brain involved in the control of movement, had the highest rate of growth - doubling in size over the 90-day period.
The slowest region measured was the hippocampus, a structure that plays an important part in how memories are made.
Scientists suggest this could mirror the relative significance of these skills as a young infant.
Dr Martin Ward Platt, a consultant paediatrician at the Royal Victoria Infirmary in Newcastle, told the BBC: "This is the first time anyone has published accurate data about how babies' brains grow that is not based on post-mortem studies or less effective scanning methods.
"The study should provide us with useful information as this is an important time in development."