Your baby's brain explained | 'Built from the bottom up': foetus to newborn

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The incredible journey a child's brain makes from their time in the womb up to the first month after birth. (Getty Images)
The incredible journey a child's brain makes from their time in the womb up to the first month after birth. (Getty Images)
  • From the outside looking in, all your newborn has mastered is eating, pooping, sleeping, and crying. 
  • But you would be well advised that icebergs have nothing on your brand new bundle of joy. 
  • We talk to experts who share the journey your newborn's brain has taken from the first trimester of pregnancy to the moment they're born and beyond. 

By the end of the first trimester of pregnancy, babies are typically no bigger than a plum. And yet, it's around this time that crucial brain development takes place. 

"The basic architecture of the brain is constructed through an ongoing process that begins before birth and continues into adulthood. Through an intricate process, embryonic cells transform into more than one million new neural connections per second and connect to form the functional systems responsible for our children's remarkable personalities and thinking abilities," the University of Witwatersrand's Sara Naicker and Rhodes University Lecturer Sizwe Zondo told Parent24

The expert duo spoke with Parent24 about the incredible journey a child's brain makes from their time in the womb up to the first month after birth, in hopes to provide new moms and dads with a deeper understanding of what makes their little ones tick. 

Also see: Pregnancy week-by-week

Find the complete series here: Your baby's brain explained: A Parent24 Series 

'In the first few weeks after conception' 

"The development of the brain begins in the first few weeks after conception, beginning with the formation of the neural tube that will eventually become the brain and spinal cord. Within a few weeks, neurons and synapses develop prompting neural connections that allow the foetus to make its first movements," the duo explained. 

In terms of the first "developing structures of the brain," Naicker and Zondo say this includes the forebrain, midbrain, and hindbrain.

"The hindbrain includes the brain stem, responsible for the most basic functions of life - breathing, heart rate and blood pressure. The midbrain makes up part of the brain stem as well as other structures responsible for sensory and motor processing. The forebrain matures into the cerebral cortex, which takes over controlling bodily functions from the brain stem in the third trimester, begins preparing the baby for future learning, and is responsible for our children's complex thinking and behaviour later in life."

'The shape of the skull and the brain itself changes form during labour'  

By the time your baby is ready to arrive, and labour occurs, your baby's brain initiates an amazing sequence of events. 

"During labour, as the baby moves through the birth canal, their skull bones ride over each other, allowing the shape of the skull and the brain itself to change form. This head compression essentially protects the baby's brain and is one of a number of physical changes the baby undergoes during delivery," Naicker and Zondo explain. 

These processes play out in tandem with a mother's equally astonishing brain activity, Naicker and Zondo say, starting with the release of the hormone oxytocin during labour. 

According to the duo, oxytocin is released in large amounts "which helps temporarily slow down the baby's nervous system (or brain cells), so they require less oxygen and so are protected against oxygen deprivation". 

From the very start of her pregnancy up until labour and well into her second year of motherhood, a woman's brain continues to adapt to accommodate her new role. 

"Simply put, there is some shrinkage of grey matter to fine-tune neural connections in areas key for social cognition - and enhanced social cognition might help mothers decode their baby's communication and promote more responsive caregiving," Naicker and Zondo say, adding that similar changes occur in a father's brain once baby has arrived. 

"New research is also pointing to hormonal, brain and behavioural changes in new fathers as they interact with their baby."

Must read: Building your baby's brain: They may inherit good 'material' but what makes or breaks the quality?

'A critical and sensitive period'

While your newborn may be spending most of their time asleep (up to 17 hours intermittently), don't let these sleeping beauties fool you. Their brains are firing on all cylinders. 

"During the earliest months, a child's brain is at peak neuroplasticity - a critical and sensitive period Naicker and Zondo tell us, further explaining that during the early months "brains are built from the bottom up - with simpler neural connections and skills forming first followed by more complex ones." 

"Some of the milestones in a newborn's first month include raising their head while laying on their stomach, keeping hands in tight fists, focusing on faces and objects, and reacting to noises," Naicker and Zondo advise while noting that babies will reach these milestones "at their own pace, as their brains and bodies mature".

Naicker and Zondo advise parents to rely on their instincts if they suspect developmental delays so that "problems can be detected and treated as early as possible". 

Also read: 29 Surprising ways you can give your baby's brain a major boost

'Genes and social experience shape the neural networks of the developing brain' 

Another critical element for parents to understand is that while "genes provide a blueprint for the brain... experiences and environment handle the construction," Naicker and Zondo say. 

Consequently, parents should view themselves as "a particularly critical ingredient" to their newborn's brain development. 

"We have come to understand that the interactions of genes and social experience shape the neural networks of the developing brain... While the foundation and structure of the brain are built prenatally, brain function itself continues to develop driven largely by... the interaction between babies and their parents - along with other caregivers in the family and community."

On the flip side, "if responses are unreliable or inappropriate - the brain's architecture and neural connections do not form as expected, which can lead to disparities in learning and behaviour", Naicker and Zondo warn.

'Adverse experiences early in life can impair brain development' 

"Adverse experiences early in life can impair brain development with negative effects lasting into adulthood. There are a range of adverse experiences including early stress, poverty, neglect, maltreatment and exposure to violence, and when these occur cumulatively, they have a stronger and longer-lasting impact."

The biggest takeaway Naicker and Zondo shared with us on how parents can maximise their child's brain development early on is simply by providing their newborn with "loving, consistent and stimulating interactions" in as positive of an environment as possible. 

"Parents are the primary source of nurturing care that cultivates a growing brain, a child's environment - whether positive or negative - in the early years, beginning at conception, has a lasting effect and forms the foundation for lifelong health and well-being."

Next: Your baby's brain explained | From language to the remarkable way 'the brain reorganises itself

Find the complete series here: Your baby's brain explained: A Parent24 Series 

Our experts: 

Sara Naicker is a research manager and PhD candidate in the DSI-NRF Centre of Excellence in Human Development at the University of Witwatersrand. Sara's research focuses on the short- and long-term biological and social effects of adverse childhood experiences and interventions to promote early childhood development. 

Sizwe Zondo is a Lecturer at Rhodes, and PhD Candidate in Psychology at the University of the Witwatersrand. His research focuses on paediatric HIV, neuroplasticity and understanding the neural networks responsible for attention and executive functions in children.   


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