What is normal development?

Every parent keeps a keen eye on their little one’s development and concerns mount quickly when your child looks like she’s behind the pack.

Paediatrician Dr Anne Tait takes a closer look at the process of development, including what's 'normal' and what could be a red flag.

Child development is the topic of many a coffee-group conversation. People tend to think of it in terms of key milestones and the age at which they are achieved. A child’s first steps, hopefully in front of a camera and recorded for posterity on Facebook, often come to mind. However, rather than being thought of as a series of isolated achievements, development should be seen as a continuous progression of interrelated skills that our brain, nervous system and muscles are able to do.

Development can be broadly broken down into four main areas: gross motor skills, fine motor skills, language and social development. I will focus on motor skills in this article, as language and social development are an article in themselves.

Walk before you run
Development happens in a very sequential manner – head to toe development and also trunk to extremity development.

In principle, control of the head must precede control of the trunk and then control of the extremities. You need to be able to hold your head balanced in the midline before you can sit, before you can stand independently, before you can walk and then before you can run and, later, ride a scooter. The same progression needs to occur for fine motor skills. You need to be able to bring your hands together in the midline before you can reach purposely for objects, before you can exchange them between your hands, before you can write with a pen and before you can play the piano.

The maturation of the brain (complete by about 25 years of age) is what happens in development. A functioning peripheral nervous system and muscles are also vital in the development process. Skill development not only requires the brain to be able to control the muscles that can complete the tasks, but the brain also needs to be able to coordinate the various muscles doing the task; to control attention to the task (ie not be distracted); to coordinate hearing and vision to enable the task to be done; and to control any fear reactions to completing the task. This peripheral nervous system is also needed to send signals to our muscles so that they can contract and relax in a coordinated manner in order to do the movement (ie walking). This entire circuit needs to be functioning for sending out and receiving signals in order for development to progress. Any interruption problem in the circuit can mean that development does not progress the way it is expected to, or it can be delayed from what is considered to be normal.

Development also does not occur in a vacuum, but rather in response to the child's environment. By environment, I mean the loving, nurturing and supportive home provided by parents and caregivers. Development can be thought of as the brain and body developing new connections in response to the stimuli that they are receiving. Children who grow up in a richly nurturing environment that allows them to explore, play and experience new things have optimised development opportunity, even if they have medical issues that could hinder their development.

We also know that, sadly, the converse is true: environments that are neglectful with exposure to domestic violence, poverty and other significant toxic stressors can have a significant negative and ongoing impact on a child’s development.

Keeping a close eye
Medical professionals use various tools and scales to assess development. I actually begin a child's developmental assessment from the moment I first see them in the waiting room, even if they came to see me for a completely unrelated issue, as this is an important part of the general screening process to ensure early detection of any issues that might not immediately be apparent. Developmental delays can occur in up to 15% of children and they can be isolated (ie one domain of development delayed) or global (ie two or more domains being delayed).

Each skill learnt has an average age, but it is more helpful to know the age limit within which 97% of children have achieved that skill.

As I mentioned earlier, it is important to realise that, while variations are observed, development should never be seen in isolation but rather as a whole system approach. If there is any concern that a child is delayed in development or has not achieved a certain milestone (eg walking), it is important to go back and look at the full history, including pregnancy and delivery, as there may be clues present that can explain what is happening. It is also important to understand that there are variations of normal and not to put too much weight on the delay in one skill, provided everything else is progressing well. For example, not all children crawl, but all children do need to learn how to sit. Also, children who are bottom shufflers are often late walkers (ie at approximately 24 months as opposed to 10-16 months), but this does not mean that they have gross motor delay. This illustrates that the ‘checklist’ approach to development isn’t as effective as ongoing developmental surveillance, which your Well Child provider will be doing over time.

Growing concerns
If a parent or caregiver has any concerns about a child being delayed with gross motor and/or fine motor development, then it's important that they get this checked out early. The first port of call would be Plunket or your GP, and if there is ongoing concern, a paediatrician would need to be consulted.

A full clinical examination is sometimes required to assess all areas of brain function, such as hearing and vision; the cranial nerves; peripheral and central tone; muscle power; and reflexes.

Development never occurs in a smooth trajectory and there can certainly be some degree of 'fits and starts'. Often, by the time I get to see some children in my clinic, they have already achieved the skills that were of concern and they are at the level where I would expect them to be. This does not mean that the consultation was a waste of time though.

The reassurance and explanation of what is 'normal' is a very important part of my role. It is also a chance to screen other developmental milestones. I usually take the time here to offer some extra education as well (such as encouraging the use of play, language, music, and most important of all, parental involvement in the child’s activities) which can be used to optimise ongoing development.

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A look at the causes
Gross motor delay can happen as a result of malnutrition, neglect and severe iron deficiency. However, it would be unlikely for gross motor delay to be the only symptom in these cases –usually other developmental domains would be affected as well.

A child may have gross motor delay as a result of damage to the motor areas of their brain, resulting in cerebral palsy. Cerebral palsy is an umbrella term for a group of conditions characterised by 'non-progressive brain injury' that impact on the body’s ability to coordinate movement. It is usually acquired prior to birth and, although the cause is unidentified, it is likely due to an injury to the developing brain. Cerebral palsy can also be acquired at birth or even as a result of an injury to the brain in the first two years of life.

Approximately three in 1000 children have cerebral palsy.

Early identification and intervention is important, as there are many treatment approaches – a diagnosis of cerebral palsy is not an endpoint. Many children with cerebral palsy have such mild impairments that most people wouldn't know they have the condition. Most can attend mainstream school and participate in normal life with minimal restrictions. Some children will have severe impairments, but all children can make developmental progress.

Gross motor skills may also be delayed from conditions that cause muscle weakness, such as muscular dystrophy or spinal muscular atrophy. Syndromes such as Down’s will also affect development, as can underlying medical conditions like congenital heart disease, hypothyroidism and metabolic disease.

All of these conditions will require careful assessment as well asexpert care and assistance. Professional input that will help with the child’s development usually involves a physiotherapist and/or an occupational therapist, who will teach parents the best strategies to use daily to help optimise their child’s development.

Finally, some children can have conditions called dyspraxia or benign hypotonia. Both of these conditions are 'diagnoses of exclusion', meaning that other conditions need to be excluded before these diagnoses can be made. Dyspraxia is where there are difficulties in the control and coordination of voluntary muscle activity, which is not due to a medical condition. A child might have some mild delays, but could generally catch up. Benign hypotonia is where some children are a bit floppy or have low tone, but still achieve the developmental milestones at the usual times.

These children might benefit from physio and/or OT input to help with their skills, but simply playing in a variety of situations and sports can be equally beneficial to improving their developmental skills.

Finer detail
Fine motor skills (involving movement of the hands in manipulating objects) are also important, but usually are not the sole presenting complaint of a medical condition. Fine motor skill development requires gross motor development, vision and coordination.

Impairment in these skills can have an impact on schooling, as fine motor skills are involved in class activities. Early hand dominance prior to 18 months of age is a red flag and should be reviewed.

Concluding thoughts
While I have mentioned some potentially alarming scenarios in this article, hopefully I leave you with an overriding realisation of what a phenomenal process child development is. Development does not occur in isolation, but is the end result of the maturation of the brain in response to the environment it lives in. A number of medical conditions can present with ‘developmental’ delay, and ongoing surveillance over a child’s life will hopefully mean that this is picked up early in order for intervention to be started promptly. The brain is constantly changing and developing over the first two decades of our lives, so directed input to optimise development is never too late for any child. Every child has the right to be able to develop to their full potential.

Children can't learn developmental skills from television and other electronic devices. Minimising screen time is something I’m quite passionate about and regularly discuss with my patients. Screens are an increasing part of even very young children’s lives and we do not yet know the full extent of repercussions for later on in life. While playing on ‘educational’ apps may appear to be beneficial for a child’s fine motor skills, we do not know the consequences this may have on other aspects of development, such as attention and concentration, as well as the interplay between fine and gross motor development. What’s more, screen time is correlated with obesity development. 

The following red flags should prompt an assessment:
Caregiver concern
●  Floppiness or stiffness in tone
●  Asymmetry of movements
●  Loss of previously acquired skills (regression)
●  Persistent toe-walking
●  Head lag on pull-to-sit at six months of age
●  Not reaching for objects by six months of age
●  Not able to hold an object placed in hand by five months
●  Not sitting unsupported by 12 months of age
●  Hand dominance prior to 18-24 months of age
●  Not walking by 18 months of age
●  Not running by two and a half years of age

Dr Anne Tait is a general paediatrician employed at Starship Children’s Hospital who also works in private practice at Auckland Medical Specialists. She has an interest in all areas of children’s health and wellbeing.


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