Brain development by numbers
The BRAIN magazine
1:1000
is the risk of a baby having a neural tube defect, like spina bifida.
This can be reduced 1/3 with daily folic acid intake.
About 5 weeks
after conception, the first neurons are produced.
At 12–14 weeks
an embryo makes new nerve cells at a rate of about
15 million each hour.
At birth, a baby’s brain is only a quarter of the size of an adult’s brain.
One year is the time it takes for the newborn’s brain to double in size.
One million neural connections form each second in these first few years.
Neural stem cells will go on to make more than 100 different types of brain cells.
By age 3
the brain has reached 80% of its adult size and
has around 1000 trillion synapses.
By age 5
the brain is 90% of its full size.
500 trillion is the number of synapses in a teen brain.
13–14 years is the age at which the brain reaches its full size.
The peak age for onset of any mental health disorder is 14.
1 in 12 adolescents hears voices or hallucinates but is not mentally ill.
100 billion
is the estimated number of neurons in the brain.
There are 37 trillion
cells in a human body.
