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Health and Wellbeing
A Health and Well-being Wales Partner

Child development is the term used to describe the cognitive, emotional, physical, social and educational growth of a child from the moment it is born through to adolescence.

(Cognitive development refers to a child’s gradual understanding and knowledge of the world through thought, experience and the senses.)

The early years (0-5) are particularly important for a child’s development. Young children thrive in loving and safe environments, with responsive parents who talk, read and play with them.

Developmental milestones

Babies develop very rapidly in their first few years and usually reach certain milestones – picking things up, sitting up and saying single words – at roughly the same age.

Health visitors are responsible for assessing a child’s early development and use certain milestones to check if a baby or young child is developing at a normal rate. These are not hard and fast – some children walk and talk earlier than others – but they help highlight any development problems early on.

Parenting. Give it Time outlines what you should expect your child to be doing at certain ages.

Your health visitor will assess your child’s development at regular intervals: at birth, at 6-8 weeks, one year and then between two and two-and-a-half years.

Speech and language

Developing speech and language skills are crucial if a child is to reach their full potential. They need to be able to communicate to be able to learn at school, socialise with family and play with friends.  

Most toddlers can say at least six words by 18 months and around 50 by the age of two; however, this can vary a lot and slow talkers usually catch up.

You can help your child learn to talk by talking to them from birth, playing with them and reading to them.

Some children may have difficulty speaking or even understanding language. Sometimes a child’s language skills are delayed due to an undiagnosed medical condition or a learning disability. Others may have difficulty with certain speech sounds. A small number of children have physical conditions which mean they are physically unable to speak.

Flying Start teams include speech and language therapists. Contact your local Family Information Service to find out if you live in a Flying Start area.

I Can's Talking Point has lots of information for parents to support their child’s speech and language skills, including an enquiry service for parents.

Developmental delay

Some children develop more slowly than others the same age, e.g. premature or very poorly babies. Children who have been very ill may even regress temporarily, although they will usually catch up when they have recovered.

Often children are more advanced in one area, e.g. language skills, while being slower to do other things, e.g. walking. It’s not unusual for a child’s development to slow down after the arrival of a new sibling.

Delayed development – or delay in one specific area of development, e.g. speech or physical skills – can be the first sign that your child has an underlying medical condition so it’s important to discuss any concerns you have with your health visitor or GP.


Children reach puberty at different ages too. The average age is 11 for girls and 12 for boys, but it can start as young as age eight (girls) or age nine (boys). The majority of young people will have started puberty by 14.

If your child starts puberty earlier or later than this age range, it’s always wise to seek advice from your GP who can arrange tests to rule out any medical problem.

More information

Parenting. Give it Time has tips to help you support your child’s development throughout their first five years.

Flying Start Wales has put together packs in English and Welsh to help parents talk to their young children.

Last updated: 21/02/2023