CHAPTER 7: PHYSICAL DEVELOPMENT OF THE INFANTLEQs: -How does an infant develop physically during the first year?-What is the order in which an infant develops motor skills?

PHYSICAL GROWTH With the help and care of others, babies

develop physically during the first year. A human’s physical growth is completed at 20-21 years.

Just as babies grow quickly during the neonatal and prenatal stages, they grow quickly during their first year. Good physical development is important during this time.

SKELETAL GROWTH The skeletal system is made of bones and

teeth. Skeletal growth refers to the changes in length, weight and appearance of teeth.

LENGTH AND WEIGHT The baby’s length and weight changes a lot

during the first year. Changes happen so quickly people actually notice on a daily basis that the baby is growing.

All children grow at their own rates. The average length of a baby is 20-21”. Most infants reach 1 ½ times their birth length during the first year. Babies usually double their birth weights in 4-5 months and triple them by the first year.

By about 9 months babies become chubbier. Fat tissues under the skin have increased.

Boys have more muscle length and thickness while girls have more fat.

FAILURE TO THRIVE The rate of growth is actually more important

than the actual length and weight. As long as the rate of growth is constant, doctors probably wont be concerned. Sometimes though, babies experience a failure to thrive. This means their rate of growth slows considerably. This may indicate a health problem.

Causes: diseases that prevent nutrients to be absorbed or

expelled The baby’s food is not providing enough nutrients Feedings are offered too infrequently The baby is abused or neglected

BODY PROPORTIONS Babies do not look like small adults. They

have different body proportions. (the Infants head is ¼ its total body, the forehead of an infant is wider than the chin. The jaw is smaller and slopes backward.)

From birth-6 months the infants head is larger than the chest. The difference in the distance around the chest as compared do distance around the head continues to increase with age.

Babies are “pot-bellied” and have short legs.

BONES AND TEETH The infant skeleton is mainly made of

cartilage. This is why infant’s bones do not break easily. There are large spaces between their bones to help joints bed easily without breaking. Young babies can suck their toes with no trouble, but cannot sit or stand because their skeletons are not sturdy. Because of their softness, an infant’s bones can easily become misshapen. Lying in one position can flatten the baby’s head in one place. This has become more common with the recommendation of putting babies to sleep on their backs to prevent SIDS.

TUMMY TIME! Changing a baby’s position during waking

hours can keep the head from flattening. Many doctors now recommend tummy time for babies. Once babies can hold their heads up (2-4 months), they should spend time on their stomachs while alert. This encourages the development of motor skills (rolling over, reaching and crawling), and it also aids bone growth.

CHANGES IN BABY’S BONES DURING THE FIRST YEAR The length of the bones increase Ossification begins. (the depositing of

minerals calcium and phosphorus) Ossification helps the skeletal frame become sturdy. This helps the infant sit and eventually walk.

The number of bones changes. Ossification in the skull results in several bones becoming one skull bone. Ex) hand/wrist: 3:28 infant/adult ratio

TEETH Teeth are a part of the skeletal system and

begin to form in the 6th week of prenatal life! By birth, all 20 deciduous teeth (nonpermanent) and a few permanent teeth are developing in the jaw.

Most babies begun cutting teeth during the second half of their first year. The sequence of teething is easier to predict than when teeth will appear.

MOTOR DEVELOPMENT Motor development is the use and control of

muscles that direct body movements. Learning to use and control large muscles helps babies crawl and walk. These abilities are called gross motor skills. Being able to control small muscles such as hands and fingers leads to the development of fine motor skills.

THE PATTERN OF MOTOR DEVELOPMENT Babies must move slowly because they must

think as they move Babies’ reactions develop from general to

specific. Motor development occurs in 2 directions.

The first is from head to foot, the second is from the center of the body to the outer extremities.

HEAD-TO-FOOT DEVELOPMENT This type of development occurs before birth.

The unborn baby develops a head, then arm buds, and then leg buds. At birth babies have well developed facial muscles, but less developed leg muscles. This is why babies can suck but not walk.

Pg. 210, Figure 7-3 shows the sequence in which babies can control their head, neck and trunk muscles. These are called milestones in the infant’s motor development.

Experts use the average of this range of ages, called an age norm to predict when babies will develop certain skills.

HEAD AND NECK CONTROL Newborn’s heads need to be supported

constantly. By 2 months they spend a great deal of time with their heads and chests raised.

By 3-4 months eye muscles are well developed, permitting babies to focus on objects in any direction.

Head control is almost complete when babies are about 6 months old.

TRUNK CONTROL This develops more slowly than the control of

the head. Babies placed on their stomachs can lift their heads before they can lift both their head and chest. Trunk control permits babies to achieve 2 major milestones: rolling over and sitting.

ROLLING OVER Between 2-5 months babies learn to roll over.

Usually they roll from front to back because it’s easier to lift the head and trunk when on the abdomen than on the back.

SITTING This development takes several months. The

baby must gain strength in the neck and back. They must also be able to control their head. The can sit briefly with support at 3-4 months of age, but by 7 months most can sit for a short time without support. By 9 months most babies can sit without support.

LEG CONTROL