You might think that all your newborn baby does is eat, sleep and have her nappy changed. But she's busy doing something else incredibly important – she's growing her brain at an incredible rate.

Want to understand why she behaves in a certain way? You're in for a few surprises…

Her brain works harder

Human infants are born at an early stage in their development. This means your baby still has a lot of growing to do. Her brain grows more rapidly between birth and the age of three than it ever will again.

It doubles in size in her first year and, by the age of three, it will have already reached around 80 per cent of the size it will be when she's an adult.

Want to make your baby's brain grow even more? Then give her a cuddle! Research shows babies who are frequently cuddled have a thicker part of the brain called the "hippocampus", which leads to improved focus and memory.

A baby's brain doubles in size in her first year. (Image: Getty Images)

She’s born with a memory

A baby's brain begins developing in your womb and she can hear the outside world around from the third trimester. This means she arrives knowing your voice.

Although a newborn can only see at a distance of 30cm, she'll feel comforted by the sound of your voice even when she can't see you.

She’s a language genius

The optimum period of time for learning languages is from three months before birth until around the age of five years.

Right now, her brain is tuning into the rhythms and nuances of everything you say, and noticing different sounds, which we think of as words, being used in different ways.

She’s obsessed with your imitating her

Your baby is born with a brain that's interested in other people's faces, she'll pay attention to them, reading and interpreting them. And she'll look from patterns from birth – for example, if she sticks her tongue out, she'll notice if you reply by imitating her.