Growth in the Toddler and Pre-School Child

Your child's growth is actually slowing down in its rate all through the years of toddlerhood and childhood. The amount of weight and height gained by your child gets progressively less over the years until adolescence - although of course overall he is still getting bigger all the time. During young childhood, other interesting changes, some noticeable and some less so, will also be taking place. The most obvious will be the changes in proportion. The head looks smaller in relation to the rest of the body; the arms and legs, fingers and toes grow longer; the limbs straighten out; the fat baby tummy becomes flatter; the face acquires its own unique characteristics and loses its baby chubbiness. Less visible changes occur in your child's bones, muscles, brain and nervous system.

Bones

The number of bones are still not complete when your baby is born: a one-yearold has only three bones in each wrist and hand; an adult has twenty eight. The bones steadily become harder through childhood: the bones of the hand, wrist and head harden quite easily, but the long bones of the arms and legs do not become completely hard until the late teens. It is because his bones and ligaments around the joints are so soft that your baby can curl himself up into positions that would be quite impossible for an adult. In addition, the tone of the muscles is poor, which is the reason he is `floppy' to start with and cannot hold his body straight until the end of the first year, or support himself on his legs without help until roughly halfway through his second year - although, as with everything about children's development, there are large individual variations. Some babies can sit up well at six months, others not until nine or ten months. Some walk before they are a year old while others do not walk until eighteen months.

The head bones in a young baby are special. He is born with several head bones joined together with soft cartilage or openings called `fontanelles' which enable the head to be `moulded' to fit into the birth canal during birth. These soft spots will gradually disappear during the first two years as the bones knit together until your toddler, like you, has confluent bone covering the brain.

As well as increasing and hardening, the bones grow in length, although different parts of the body grow at different rates. It is bone growth which contributes most to your child's ultimate height. These rates will vary from individual to individual. Contrary to what you might have heard, it is not possible to predict accurately what a child's adult height is going to be from his height at two years old. He may be three feet tall at two, but the old rule of thumb that this is half his adult height will not apply if he is an individual, for example, with medium-sized parents. In this case, he is unlikely to grow to six feet and, of course, it is extremely unlikely that a little girl will grow to this height. Boys and girls differ by 14 cm (51/2 in) in average height at the end of adolescence, but when they are toddlers there is hardly any difference at all.

Muscles and Nerves

Unlike the bones, your baby is born with all the muscles he is going to need, though they will develop in length and thickness as he grows. During childhood there is no difference between the muscles of boys and girls, but in adolescence and adulthood boys will normally develop more muscle than girls. It has been estimated that about 40 per cent of the final body mass of a man is muscle, while it is only 24 per cent in a female. Muscles are responsible for the strength and flexibility of the different parts of the body. This can be increased by exercise, and of course your little girl should be given as many opportunities to exercise and strengthen her muscles as your son (boys and girls).

The brain and nervous system of your baby have a lot of rapid growing to do after birth. Some parts of the brain - those that control attention, absorbing new experience and the basic baby activities of sleeping, waking, feeding and getting rid of waste through bowel and bladder - are already working well. However, the parts of the brain that control more complex activities - controlled movement, thinking, language, understanding - go on developing after birth and are nearly, but not altogether, complete by the time he is two. If you think how competent a two-year-old child is compared to a newborn baby, you can see for yourself how many changes have had to take place in his brain and nervous system in order for him to do the running, holding, planning, talking, demanding and controlling that he can do now.

The brain controls the activities of the body through the nervous system. At first it cannot do this very well because the nerves, particularly those at the extremities of your baby's body, take some time after birth to become fully equipped to carry the brain's messages. Nerves have to be covered with a special sheath called `myelin' in order to communicate effectively with the body parts that they control. The process of myelinisation in the nervous system outside the brain takes up to two years to complete and is not complete in the brain itself until the end of adolescence. Once the nerves are sheathed in myelin they can help your baby to control his movements much more effectively You will notice that this process does not happen all at once - the baby gains control of his head first, then his limbs and trunk, and finally he gains the very fine control of fingers and limbs which enable him to do delicate and complicated tasks such as building with small bricks or holding a pencil and writing. As his nervous system matures he will also learn to gain control over bowel and bladder movements. There is more about this on toilet training, but the important point to remember is that your baby.cannot control his behaviour as you might like him to until his nervous system has gained the necessary maturity. This takes time.