Your babies development

Important brain development occurs in the first years of a child’s life.

As a parent or guardian, you can support your child’s early development by providing a safe and nurturing environment, with gentle care, touch, speech, and play.

Antenatal (before your child is born) – Your child’s brain has already started developing. All five senses begin to function before birth and sensory experiences (e.g. what they hear) can help shape the brain and nervous system.

Find out how your baby is developing in each trimester and about your baby’s sensory and brain development.

First Trimester

You and your baby building the most amazing human body

Your baby’s primitive heart begins beating at about day 22 after fertilisation enabling very primitive blood cells to circulate, and this makes the heart the first functioning organ system.

Within weeks after conception your baby’s brain is beginning to bulge and will be given a high priority in the period of growth both before and after birth.
Your baby will be having a range of sensory experiences in response to what is going on inside and outside your tummy. Your baby will be able to respond to sound, vibration and vestibular (balance) changes – as you move, your baby responds accordingly.

Emotional development of your baby begins long before its first breath of air.
Towards the end of the first trimester your growing baby begins to leap and use the walls of your uterus as a trampoline.

By week 9

Their fingers and toes are almost complete and they have touch pads on their fingers.

By week 10

Your growing baby contains all the organ structures that a new-born baby has, but in an immature state.

By week 11

Your baby’s body length has doubled and all vital organs are fully formed. Other coordinated activities such as stretching, swallowing, yawning and sucking are beginning to enlarge.

Second Trimester

Continuing to build the most amazing human body

Movement is your growing baby’s primary activity. They can bend, flex, twist, stretch and kick, as well as suck, swallow, yawn and grasp.

Rapid growth of the part of your baby’s brain associated with movement and balance enables your growing baby to practice increasingly more coordinated activities. Due to extended connections from the brain to most parts of the body, baby can perform somersaults, back flips and rolling movements in the next few weeks.

With surprising development of hearing and tasting the way is open for babies to have even more extensive interactions with you.

Life in the womb – now we can observe it – bears little resemblance to the lazy world we once thought happened in which a growing baby was an inactive passenger, virtually deaf, dumb and blind.

Your growing baby’s brain is affected by environmental factors such as malnutrition. This is why it is critically important to eat well and healthily during pregnancy.

One of the biggest surprises about life in the womb is the way growing babies can feel and react. Spontaneous and graceful movement that can now be observed from about 10 weeks reveals self-expression and early aspects of self-control, needs and interests.

Third Trimester

Finishing building the most amazing human body

This final stage of your baby’s growth inside the womb is characterised by significant weight gain, your baby will almost triple in size and their length will double.
Dramatic brain growth is happening at this time, this is due to new cells and connections being made.

This is also a crucial time for the maturation of your baby’s senses, and they are literally buzzing due to the development they are undergoing.

Exploring their environment is becoming your baby’s primary source of entertainment.

Around about this time, baby’s cerebral cortex has become mature enough to enable them to feel and remember things, such as particular tunes or music.

A message from your baby…

By week 32

I can hear, taste, smell and touch. I sleep for most of the time, and during this time rapid eye movements, which are associated with dreaming, are apparent. Dreaming helps my brain to further develop, which is why I spend 90-95% of my time asleep.

By week 38

I have lived underwater, in almost complete darkness, all warm and cosy. I have experienced smell, taste, touch, and movement. I have developed a brain that is ready to learn and experience the world around me.

Baby’s brain development

The brain grows steadily during pregnancy and is about a quarter developed at birth.

  • Amazing growth takes place in infancy – it takes just seven minutes for the synapses of each neuron to form. By three years of age there are trillions of connections – twice as many as an adult has. But only those that are used regularly will remain.
  • A young child’s emotional, social and intellectual development is very rapid. Experiences shape the brain’s architecture, as the underused neural pathways are pruned away.
  • The root of many adult conditions can be traced to early childhood experiences and affect the future programming of physiological functions.
  • The development of neural pathways is influenced by genes, blood supply, hormone levels, and the physical and socio-emotional environments.

Did you know

  • Babies are born with over 100 billion brain cells.
  • Early years are crucial; the brain is 25% developed at birth and 80% developed by age three.
  • Positive stimulation will build strong neural pathways.
  • Physical, emotional and social development are all important.
  • Simple things repeated help these pathways to strengthen.

Positive relationships, play and creative activities aid brain development.

Your baby’s brain:
• Reptilian brain
• Mammalian brain
• Higher brain

Download our leaflet here

Sensory development of your baby

Proprioception (unconscious sense of body)

Development begins at 9 weeks. Constant feedback from the womb helps baby to understand its physical presence, abilities and restrictions. This is calming for the foetus, sense of separateness comes several months later.


The vestibular system (balance) begins to develop. The vestibular system is adult-like within 12 weeks. It is crucial, enabling baby to sense orientation so they can later turn head down, ready for birth.
Hearing is developed by week 22.

Taste & smell

By 16 weeks, amniotic fluid is swallowed, enabling the foetus to become familiar with the taste and smell of their mother. This helps later to establish good feeding. For this reason, perfume and strong soap may not be a good idea.


Not needed in the womb but eyes are fully developed by week 24.
At around 33 weeks, the foetus’ pupils are able to constrict and dilate.
The foetus is able to make out dim shapes and practise opening and closing eyelids.

As your baby’s develops so does their sight. Here’s how it develops after they are born.

Premature babies and development

Premature birth can affect the way your child develops and the earlier your child was born, the higher the risks, so your Midwife and Health Visitor will provide additional monitoring and support to ensure your baby develops as normally and healthily as possible. Should your child need additional support there are specialist services to support you as parents. However, it’s all about striking a balance: every child develops in their own unique way.

Development milestones are based on averages. Not meeting given milestones is not just an issue for pre-term babies. Term babies sometimes do not meet development milestones either.

Find out more about Premature labour and birth

Plagiocephaly and brachycephaly (flat head syndrome)

Babies sometimes develop a flattened head when they’re a few months old, usually as a result of them spending a lot of time lying on their back.

This is known as flat head syndrome and there are 2 main types:

  • Plagiocephaly – the head is flattened on one side, causing it to look asymmetrical (both sides of the head look different); the ears may be misaligned and the head looks like a parallelogram when seen from above, and sometimes the forehead and face may bulge a little on the flat side.
  • Brachycephaly – the back of the head becomes flattened, causing the head to widen, and occasionally the forehead bulges out.

Always discuss these symptoms with your Health Visitor. However, these problems are quite common and in most cases they aren’t a major cause for concern, as they don’t have any effect on the brain and the head shape will often improve by itself over time. Your baby won’t experience any pain or other symptoms, or any problems with their general development.

If you need further information, support or advice please look at the NHS website or call your Health Visiting team.