This article is intended to give a hopefully useful account of child development. I decided to write it to support medical students on the King’s College London Medical course, but it may be that others will find it useful. I have also included a reference table of developmental milestones to support this article. I will confine myself to 0-5 for curriculum reasons, but there is a link to my over-5s paper at the bottom of this blog.
Obviously, reading an article is no substitute for spending time observing and interacting with children, but my hope is that I can place these observations in some kind of context. This will be published as a blog with a pdf version attached for those who prefer to read papers on paper.
My purpose in writing is as follows:
To help foster an understanding of factors which influence developmental progress
To help in forming a picture of developmental expectations
To give guidance in when to be concerned; what are the ‘red flag findings’
To help professionals to know what questions to ask when presented with a parent who has concerns about their child
Part 1: How does development happen?
The human brain is the single most complex object in the universe, with something like 240 trillion connections. So its development is almost impossibly complex, and we may never understand it fully. I’m going to start at the level of brain structure and function.
What we do know, however, is that at birth the brain has more synaptic connections that in maturity. The brain at this point is in a way like a TV showing static, and it is only by structure emerging from this static that function can emerge. This occurs via the formation of neuronal networks by pruning synaptic connections, rather like when Michelangelo looked at a block of marble and took away all the parts which weren’t David..
These networks start simple. It is useful to think of a computer analogy here. When building up some software, developers start with individual ‘sub-routines’, simple loops and combinations which the combine to form increasingly functional and complex networks. The very same process occurs in the brain, only with neurones and synapses instead of microchips and code. What is amazing about the brain is the way in which structure, at a cellular level, seems to embody function.
This process certainly has its own ‘drive’ and will occur to an extent in a pre-programmed way. However, it is crucially shaped by a number of factors:
The activition of certain genes is necessary for the development of neural networks and corresponding developmental skills. With the recent advances in epigenetics is has become clear that the mere presence of a gene within the genome is not sufficient and its expression is governed by a number of factors.
It seems that the brain’sneuroendocrine environment, that is the composition of hormones and neurotransmitters that bathe the neurones, is a key determinant. One good example of this is the emergent work examining the adverse effect of chronically high cortisol on the limbic system.
Of course, sensory and emotional inputs (translated of course to patterns of neural impulses)are crucial in shaping the way that these neural networks develop. For instance the newborn’s ability to understand human speech is limited at birth, but quickly develops by verbal interaction along with social interaction with their carers, such that even very young babies will respond more strongly to their native tongue.
Under the influence of this process, the relatively purposeless reflex movements and vocalizations of the newborn start to take on more discernable purpose, with the onset of developmental skills.
How do particular skills develop?
To answer this it is most useful to think at the level of the individual, although of course changes occur at a neural level also.
In order to develop a new skill, children must:
Want something: A motivation to explore and interact is a given for most children, even those that are quite severely disabled, but previous frustrations/ lack of feedback will have an effect on motivation,
Try something: It is important that carers give the child the freedom and opportunity to explore their environment for themselves
Sense result: using all senses and developing social understanding
Get feedback: the object being explored will do this sometimes (e.g. biscuit tin opens), but the process of feedback needs to be guided and amplified by carers.
Try something different: If something doesn’t work, most children will use trial and error until it does. This is a much more powerful process in the under 5s than instruction.
This list might seem like common sense, but a lot of problems with parenting are caused by a failure to appreciate its implications, and either restrict opportunities, give inadequate feedback, or try to control too much.
Variance in developmental attainment
Norms have been established around a large number of key skills (see document below), but within these there is wide variance. Why?
This is a difficult area- certainly some patterns of development (e.g. slightly late walking due to mildly low tone, mild isolated expressive speech delay) tend strongly to run in families, but it would be a mistake to assume that just because, say, all members of a family have struggled at school that this is a ‘genetic problem’. There may be modifiable socio-economic factors at play.
Environmental factors restricting potential
Maternal physical health, and the mental health of either parent has a demonstrable effect on child development, probably by interfering with feedback and developmental opportunity.
Socio-economic conditions have a powerful effect- some studies have shown up to a year’s difference between developmental attainment in the highest and lowest income group. However, the precise mechanism for this is not clear.
Abuse and neglect have a powerful negative effect on child development: the chronic fear engendered by physical abuse acts both at a neuroendocrine level (as above) and by decreasing motivation to explore. Neglect is more subtle, and is very frequently a consequence of parental mental health problems
Acquired pathology reducing potential
The in-utero environment is crucial for neurogenesis. Factors such as maternal stress and diet are important, as well as the presence of alcohol, nicotine and some illegal and legal drugs. Intra-uterine infection is fortunately rare but can be devastating
Birth is a highly vulnerable time for the developing brain and a hypoxic insult at this point can arrest some or all brain development, particularly in ‘watershed’ areas of cerebral perfusion such as the motor cortex. After birth, any serious illness can have an effect (for instance, there is a greatly increased rate of developmental problems in congenital heart disease), but meningitis and encephalitis have an obviously strong direct effect on development.
Finally, there are a dizzying variety of specific genetic conditions which can cause developmental delay. To describe these is beyond my brief, but most children with developmental delay do not have one of these syndromes, and instead have a combination of the other factors mentioned above. Interestingly, as our ability to scrutinize the genome in ever-greater detail increases, more subtle abnormalities of genomic code and expression will emerge, either as a sole cause or, more likely, as another element in a complex causal network.
How do we describe development?
For convenience, we split development into several ‘domains’. It’s important to note that these domains overlap and are mutually dependant.
Gross motor (large movements and locomotion)
Fine motor & vision(eye-hand coordination, also planning sequences of movment)
Language (receptive or expressive)
Social development, behaviour & self-help skills (the transformation of the child into a socialised member of their society)
Cognitive development (underpins all other aspects to an extent)
Growth, special senses (hearing, vision, etc)
What is developmental delay?
Broadly, this can be defined as a failure in the acquisition of expected skills, which leads to functional impairment for the child
The term expected is important. Expectations occur in the timing and order of developmental achievements, and also vary between cultures and historical eras. For instance, handwriting is highly prized in today’s society, but was a minority pursuit 400 years ago, and may be again sooner than we think!
Impairment is key- if there is no impairment then diagnosing delay is a purely academic exercise. The scope of impairment is very wide, though, and may be physical, social, communicative, emotional or academic
Degree of developmental delay
There is surprisingly little agreement on this: one useful measure (I have found) is the developmental quotient.
The DQ = Age of developmental attainment divided by chronological age
So a child who in language terms is operating at a 3 year level aged 4 has a DQ in this domain of 0.75. This is a rough measure that allows you to decide which children to investigate further, potentially can guide intensity of therapy, and provides some limited guidance for parents on possible outcome, as the DQ tends to be fairly stable over time, at least into middle childhood.
This is ‘the meat’ of this post- I will now try to give an account of how the child’s skills develop. I might suggest that students read it with a copy of the reference table of developmental milestones to hand.
At birth babies can recognise bright lights and, amazingly, faces. They can even tell a face-like scribble from a more random arrangement. Over the first year they start to see progressively smaller objects, until at a year they can spot a sweetie from several yards! Of course, good vision underpins fine motor abilities as well as social communication.
Fortunately, parents are very good generally at spotting visual impairment,as the child will often fail to respond as well to environmental cues. Nonetheless we need to be very careful to examine visual responses, especially with young babies.
Babies can hear at birth, and will ‘startle’ to loud noises. By 6 months they should be turning their head to sound, as their hearing becomes more acute. Hearing underpins language acquisition.
Hearing is screened for just after birth, and the screening is pretty good at picking up sensori- neural deafness. However.it will not pick up acquired problems leading to conductive deafness.
Gross motor development
0-1yr: The battle with gravity.
Progress in this year can best be thought of as a slow raising of the child’s centre of gravity, brought on by improvements in tone and control in pairs of muscles running down the centre of the body. This process occurs first in the head and neck, allowing the head to be raised in a prone position from 3 months, before progressing down the body to the shoulders and trunk (allowing rolling at 4-5 months), them the pelvis (sitting at 6 months), hip stability allows crawling at around 9 months, and toddling begins with cruising between objects just before a year. This process should be symmetrical, so a clear preference for using one side of the body is a worry at this point and should be investigated.
1-2: Toddle to walk.
Toddling is a broad-based, flat-footed gait during which the feet only get a very short distance off the ground.it is therefore not very good if you need to speed up (by increasing strife length), turn (by pivoting on one leg), or climb. Essentially what happens in this second year is the evolution of a more mature gait capable of these skills.
2-3: Jump, throw, kick.
So by 2, the child has control over direction and speed on the ground. The next step is to leave the ground, or cause other objects to do so. Initially this is highly inaccurate, but by 3 the child is able to throw in roughly the intended direction, and jump off a step without tumbling.
3-4: Vehicles, catch, climb.
The next stage is to gain control, improve precision of movements, and start to sequence them together to functional ends. The child at this point starts to be able to ride a trike by pushing either against the ground or later on pedals. The child places her limbs on successively high support points and thus is able to climb a frame. And the ability to anticipate the future position of objects (cognitively driven) allows for the beginning of catching
4-5: Control, co-ordination.
Essentially, by now major motor problems will have come to light, and the normal child will progress onto moresophisticated tasks. Balance improves and children start to be able to ride a bike. Sports can be played in groups, which of course also requires social skills. In clinic, the child will be able to stand on one leg for 10 seconds, catch a ball thrown from a couple of metres, and return it accurately (but not all at the same time!).
Fine motor development
0-1 “A very grabby little person”.
In the first year, babies basically learn to get things into their hands. In the first six months, this is mainly batting at objects with occasional grasp due to reflex hand closing, but about six months, the palmar grasp emerges. As you might expect, this is a grasp which holds the object in the palm, and the next six months is spent developing the ability to hold objects further and further down towards the fingers, culminating in a pincer grip at about a year. This grip allows small objects (e.g. Smarties) to be held between two fingertips. Meanwhile, at around 9 months, the baby learns that objects continue to exist even when out of sight. This crucial step, known a object permanence, allows them to start constructing a mental picture of the external world, a tool that is crucial in all sorts of ways, as will see. What you should NOT see at this age is a hand preference.
During the second year of life, the child becomes increasingly adept at placing objects accurately. This is important functionally for finger-feeding, and the beginnings of contruction play. The point is not just that they are able to get the object where it needs to be, but also become able to slow their approach, and release objects precisely using a co-ordinated movement of the fingers. The easiest way to test this skill in clinic is to ask them to build a tower of blocks.
At this point the child can control not only the destination of a movement, but also its trajectory. This enables spoon-feeding, and drawing begins, with scribbled circles. The child can begin to help in dressing (e.g. putting arms through sleeves of a jumper).
3-4 Two hands:
Of course both hand have been used up till now, but the big change at this point is the ability to use both hands to do different things for the same purpose (you will see of course that this is also a cognitively rich task). This allows more sophisticated building, drawing stabilised by the other hand on the page (allowing proper circles), and some eating with two pieces of cutlery (initially pancakes/ omlettes etc.).
By this time the ‘building blocks’ (no pun intended) for fine motor function are in place, and what essentially happens next is a process of refinement, with more accurate movements, and more importantly, movements sequenced in such a way as to achieve a previously visualised or imagined result. For example, a square is drawn by imagining the square, then drawing the first lines in such a way that the last lines will correctly join them. This is of course a further development of the ‘object permanence’ that emerges in the first year, and this ability to imagine, visualise and plan continues to develop into adulthood from this base.
Language and communication
It is important, when considering this area, to understand that there are actually two processes going on here. The first is the learning of language- the codes and conventions that underly the exchange of verbal information. The second process is the evolution of social communication, a set of skills developed to allow children to form and foster relationships. I go into more detail about this below, but it will come into this section as well.
There is a lot written in textbooks about different sorts of babble, cooing etc. The important things in the first year are that a) some sort of vocalisation happens b) these are directed at a person and associated with social cues such as smiles and c) towards the end of the first year these vocalizations start to sound a bit like speech.
Individual words (not just mamamama interpreted as mummy) emerge around the first birthday. At first these are few in number, but towards the end of this year there is an explosion in vocabulary- a good rule of thumb is that most parents can’t count the number of words the child has by the age of 2. These single words are converted to questions and requests by a combination of inflection, facial expression and gesture
2-3 Phrases/ commentary:
Joining two words is not quite the point here (moo-cow is not a phrase), the point is to join two linguistic units of meaning, usually a verb and a noun, such as ‘want biscuit’. At this point imagination becomes hugely important, and children will play with toys giving a commentary on what is happening. This is typically a mixture of short phrases, jargon (proto-speech) and noises, but it’s an important precursor of narrative. At the same time speech articulation improves and so the child’s speech becomes comprehensible to a wider variety of people.
3-4 Conversation/ questions:
At this point short sentences start to emerge. These are often in the form of questions, initially ‘what’s that’, but later ‘who’, ‘where’, and finally (after age 4) ‘why is…’ questions emerge. As well as requests, questions and protests, the child begins at this point to be able to manage simple conversations with a supportive adult, and with this the ability to disagree, compare and argue begins. For instance at this point use of smaller/bigger and negation (it’s not yours, it’s mine!) emerge.
4-5 Narrative/ persuasion:
Up to this point, language has mostly been used to describe or influence the here & now, but at this point the child starts to be able to describe distant events; two skills help here- one is the use of tense, and the other is the ability to imagine what the person listening does and doesn’t already know, and tailor what is said accordingly. So for instance a child might at this point know to describe who someone is when introducing them to a story. The other important skill at this point is persuasion- this sophisticated exercise requires knowledge of others’ states of mind, as well as social conventions and expectations. Girls are better at it at this point, and arguably remain so.
This is the evolution of the child from an organism exclusively concerned with and equipped for its own survival, to a junior member of society, nested in the context of family, community and school.
The social ‘task’ of an infant is to form and maintain an emotional bond with one or more reliable caregivers. They do this by the evolution of attachment behaviours- smiles, eye contact, crying & (later) gesture designed to increase physical and emotional proximity. The response of caregivers is crucial- should they fail to respond or respond in a frightening way this ‘attachment system’ can develop in a disordered fashion, which may have dire consequences for the child’s later socialisation.
1-2 Showing & social communication:
At this point the child becomes more aware of their ability to induce social responses in others (not just their primary caregivers). They do this by a variety of verbal and non-verbal means, among the most important of which is ‘joint attention’, by which the child can use eye contact to guide another person’s attention to a desired or interesting object. Play starts to emerge at this point, and is mainly cause & effect in nature (e.g. pushing a car along or bashing a button to make a light come on), but most children enjoy turn-taking with an adult, and some imitation of domestic activities (e.g. using a toy phone) starts to emerge.
This age is rather unfairly called the ‘terrible twos’. What happens is a dawning awareness of the child’s own separateness from the parent. At the same time the child develops a representation of how they want things to be, which is sometimes hard to distinguish from how things actually are. It’s easy to see how these factors will lead to a period of tantrums, but also to a new dimension of exploration and imagination, as the child starts to generate her own worlds in play towards the end of this year. Play is also quite physical (particularly in boys), as they explore and experiment with their physical abilities.
3-4 Friends & social interaction:
Up until now we have talked about the child in their family and playing alone- even if they are physically with other children they will usually play alongside rather than with the others. This changes after 3- play becomes co-operative, and imagination is shared and negotiated (this is the beginning of role playing). At the same time the child spends more time with peers, and starts to pick and choose which of these they prefer and want to negotiate friendships with. Adults start to find the child easier again because deals can be struck (eat your sandwich, and you can have a biscuit), and so incentives start to become effective.
4-5 The big world:
The child starts to become more aware of social convention and adult-led rules at this point. What is interesting is that most learning of rules is not explicit but by repetition and observation of the behaviour of others. This has obvious implications for parenting, but also underpins the importance of routine in nurseries and schools. Equally, the child needs flexibility of thought at this point as well as understanding of routine and convention. They need to be able to apply social knowledge to novel situations (e.g. a relative’s house they have never visited) and as play becomes more elaborate and rules start to be generated by other children, a lack of flexibility leads to conflict.
Red flags for development: Refer to child development services if you notice…
No rolling by 9 months
No unsupported sitting by 10 months
No independent steps by 18 months
No running, no pincer grip by 2 years
No jumping by 3 years
Language & communication
Failure to respond normally, such as not responding when spoken to.
No babbling by 12 months.
No first words by 15 months.
No consistent words by 18 months.
No word combinations by 30 months.
Strangers having problems understanding your child’s speech by 36 months of age.
Not showing an interest in communicating.
<1 year: no eye contact
2 years: no pointing, showing
3 years: object play only (no imagination)
4 years: no sharing,no interest in toileting
5 years: no friends, no concept of rules
How to take a developmental history:
If you’re finding all of this a lot to take in, don’t worry- when confronted with a concerned parent you can usually get most useful information from quite a simple structure, a bit of active listening and some functional questions. Let me explain…
Concerns: the concerns may be that of the referrer, the parent or the child. At this point it is important only to be curious and interested; bringing your brilliant intellect and professional knowledge to bear can wait!
Background: where the child comes from, genetically and socially (as covered above). Important aspects are:
Family history of developmental or neurological problems, mum & dad’s experience of education
Where the family members are from, what important or traumatic experiences they have had, and whether there are any problems now. (Drugs, alcohol, violence)
What other professionals are involved with the family at the moment.
This starts in pregnancy- was mum well, did she take anything at all, did she get all her blood tests done in antenatal care
How was the delivery? Was there any need for special care?
Developmental milestones: Bear in mind even attentive parents forget milestones. Do have the reference sheet provided to hand (I still do!)
Current abilities: what the child can do now.
Questions should start open, with follow-up to clarify specific information.
For instance what was she doing at her xth birthday is a good starter, as it allows the parent to visualise the child at this age, then answer more specific questions.
Asking whether the parent has ever been concerned about something is also useful. You should ALWAYS ask this about the chld’s ability to hear or see.
I find that asking about specific milestones from the reference sheet can only take you so far… what matters here is day-to-day function. So ask how she….
Gets on with other children?
Either now or in the past
Children tend to avoid things they find difficult (as do we all). So it’s worth asking in the older pre-schooler whether she likes…..
Having read the previous section on developmental progress, it will hopefully come naturally to think about what kind of skills the parent is decribing, and the child is exhibiting in clinic, and match them to developmental stage (or at lest that’s the theory)
Developmental Assessment/ Observation
We community paediatricians will supplement the history with a battery of standardised exercises to gain direct evidence of the child’s abilities. The child’s performance is then compared to age norms, and the overall picture can then be interpreted in terms of strengths and difficulties within the different developmental domains mentioned above.
This assessment is very difficult to get absolutely right, and there is always a trade off between speed and comprehensiveness. It’s an interesting exercise to watch so if you are a student do try to arrange to observe one.
However, it’s really very important to note that a LOT of the key information that we gather is picked up by being observant of what the child does, both when the centre of adult attention, and also when left to their own devices. Crucial information about social skills, relationships, and physical confidence can be gleaned, especially by a helpful and alert student sitting in!
Development is a complex process built from simple elements.
Assessing developmental problems is the same- individually the questions and exercises we do seem like chatting and play, but interpreting this volume of information makes for an intellectually challenging job.
Red flags are the only factual ‘must-haves’, so please study them closely.
Milestones are a millstone: I’ve provided a reference table, but if you are stuck, always think of the child’s function in everyday life.