Chapter 7 Physical Development of the Infant

Transcription

1 Chapter 7 Physical Development of the Infant Mason is 10 months old. Although he is large for his age, his motor skills lag far behind those of other children his age. For example, Mason has trouble sitting unassisted. How can Mason s parents encourage his motor development? What activities would you suggest? Would you be concerned? What types of professional help, if any, would you advise his parents to seek? If you were Mason s caregiver at a child care center, how would you discuss his development with his parents? After studying this chapter, you will be able to describe how an infant develops physically during the first year. describe the order in which an infant s motor skills develop. Define skeletal system failure to thrive body proportions ossification deciduous teeth motor development gross-motor skills fine-motor skills age norm crawl creeping cruising voluntary grasping With the help and care of others, babies develop physically during the first year. A human s physical growth is completed at 20 or 21 years. This growth period is longer than that of any living creature. During much of this time, others must care for the human. Just as babies grow quickly during the prenatal and neonatal stages, they grow quickly during their first year of life. It is fun to watch a tiny newborn grow into a more chubby-looking infant. Good physical development is important during this time. A healthy baby keeps growing and developing in all areas. Chapter 7 Physical Development of the Infant 205 Skeletal Growth The skeletal system is made of bones and teeth. Skeletal growth refers to the changes in length, weight, and the appearance of teeth. Length and Weight The baby s length and weight changes quickly during the first year. (The term length is used for the first year because the baby does not stand. After the first year, the term height is used.) Changes happen so quickly that even people who see the baby daily are amazed at how fast he or she grows. They can see the baby change. All children grow at their own rates. The average length of a baby at birth, however, is 20 to 21 inches. Most infants reach 1 ½ times their birth lengths (adding 9 to 10 inches) during the first year, 7-1. Babies usually double their birthweights in four or five months and triple their birthweights by one year. Usually boys are slightly longer and heavier than girls (by about ¾ of an inch and 1 ½ pounds). By about nine months, the infant becomes chubbier. This change happens because fat tissues under the skin have increased. After this time, fat tissues begin to decrease. Even at this early age, skeletal system. The body system that includes the bones and teeth.

2 206 Part 3 Infants Chapter 7 Physical Development of the Infant 207 Average Length and Weight During First Year Age in Months Birth Length in Inches 20 23¾ ½ Weight in Pounds 7½ 12½ 16¾ 20 22¼ 7-1 A baby s length and weight increase quickly during the first year. boys have more muscle length and thickness, while girls have more fat. The rate of growth is more important than the actual length and weight. The baby s doctor will use a growth chart to record the baby s growth at each checkup. This growth chart shows the average growth for babies as well as the measurements for this baby. The doctor will compare the baby s actual measurements to these averages. As long as growth seems to continue at a constant rate, the doctor will not likely be concerned. Sometimes, however, babies experience a failure to thrive. This means their rates of growth slow considerably over time. This may indicate a health problem exists. In this case, the growth chart would show the baby was growing at a steady rate and then showed a decline. Possible causes of failure to thrive include the following: diseases that prevent all or some nutrients from being absorbed or that cause nutrients to be quickly expelled from the body the baby s food is not providing enough nutrients (diluted formula or breast milk affected by mother s malnutrition) feedings are offered too infrequently or last too short a time the baby is abused or neglected With the proper care and attention, the baby s health can often be restored. The length of time this will take depends on how severe the problem was and how long it lasted. Body Proportions Infants do not look like small adults. Their body proportions (relative size of body parts) differ from those of adults. For example, an infant s head is about one-fourth his or her total length, while an adult s head is onetenth of his or her total height. Unlike adults, the forehead of an infant is wider than the chin. The jaw is smaller and slopes backward. This is commonly called the baby look. From birth until six months, the infant s head is larger than the chest. In most six-month-old children, the chest becomes larger. The difference in the distance around the chest as compared to distance around the head continues to increase with age. Besides having a large head, an infant has a long trunk, a pot-bellied abdomen, and short legs. The gain in length during the first year is because the trunk grows. The legs do not grow much longer at this time. The abdomen sticks out because the internal organs are large for the baby s small body. Because the center of gravity is high on the baby s body, the result is poor balance. No wonder babies toddle rather than walk! Bones and Teeth The infant skeleton is mainly made of cartilage. That is why infants bones do not break easily. There are large spaces between their bones to help the joints bend easily without breaking. Young babies can suck their toes with no trouble, but sitting and standing are impossible because their skeletons are not sturdy. Due to their softness, an infant s bones can easily become misshapen. Lying in one position all the time can flatten the baby s head in one place. This has become more common in recent years with the recommendation for babies to sleep on their backs. (This position for sleeping greatly reduces the risk of SIDS.) 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 (at two to four, they should spend time on their stomachs while alert. This encourages the development of motor skills, such as rolling over, reaching, and crawling. It also aids bone growth. During tummy time, caregivers should stay close and offer the baby toys to see, reach, and grasp. This stimulates the baby s brain. During the first year, three changes occur in a baby s bones. First, the length of the bones increases. Second, ossification (depositing of the minerals calcium and phosphorus) begins. Ossification helps the skeletal frame become sturdy. This helps the infant sit and eventually walk. Third, the number of bones changes. For example, the hand and wrist of a one-year-old infant has only three bones, but there are 28 bones in the adult s hand and wrist. Also, ossification in the skull results in several bones becoming one skull bone. This growth is completed in about two years. failure to thrive. A condition in which a child fails to grow at a healthy rate. body proportions. The relative size of body parts. ossification. Hardening of bones caused by the depositing of the minerals calcium and phosphorus.

3 208 Part 3 Infants Chapter 7 Physical Development of the Infant 209 upper central incisors (8-12 upper 2nd molars (25-33 upper canines (16-22 lower 1st molars (14-18 lower lateral incisors (10-16 lower 2nd molars (23-31 upper lateral incisors (9-13 upper 1st molars (13-19 lower canines (17-23 lower central incisors ( Deciduous (nonpermanent) teeth appear in a predictable pattern. Teeth, a part of the skeletal system, begin forming in the sixth week of prenatal life. By birth, all 20 deciduous teeth (nonpermanent teeth) and a few permanent teeth are developing deep in the jaw. Most babies begin cutting teeth during the second half of the first year, 7-2. The sequence (order) of teething is easier to predict than when teeth will appear (timing). In fact, a few babies are born with one or more teeth. Other children are more than a year old when their first teeth appear. Motor Development Motor development is the use and control of muscles that direct body movements. Learning to use and control large muscles (such as the trunk, arms, and legs) helps babies crawl and walk. These abilities are called gross-motor skills. Being able to control the small muscles, such as the hands and fingers, leads the baby to develop fine-motor skills. Having control over the body is a sign of babies growth and development. The baby s motor skills develop in three main patterns. This order of motor development builds upon the order of brain development. The following list shows the pattern of motor development: 1. Babies move slowly because they must think as they move. 2. Babies reactions develop from general to specific. At first, babies show general reactions to what they see and hear. Later in the first year, babies give more specific reactions. For example, if young infants see something they want, they wiggle all over. Older infants smile and reach for the object. 3. Motor development occurs in two directions. The first is from the head to the foot. The second is from the center of the body out to the extremities (from the trunk to the hands and feet). Head-to-Foot Development Head-to-foot development begins 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 well-developed leg muscles. This is why babies can suck but cannot walk. Drawing 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. Milestones are sequenced steps, and the order of these steps is more constant than their timing. How do experts calculate the timing of these steps? Some babies develop when they are older, others when they are younger. 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 Newborns need to have their heads supported continually. Their muscles are not strong enough to hold their heads steady themselves. Some babies can raise their unsteady heads briefly when lying on their stomach. By two months, most babies spend a great deal of time with their heads and chests raised. Between three and four months, eye muscles are well developed, permitting babies to focus on objects in any direction. They can smile when they want to and make some sounds with the lips. Head control is almost complete when babies are about six months old. By this time, babies can raise their heads while lying on their backs. They can also hold their heads steady while sitting. Trunk Control Control of the trunk develops more slowly than control of the head. Babies placed on their stomachs can lift their heads before they can lift both their heads and chests, 7-4. Trunk control permits babies to achieve two major milestones in motor control rolling over and sitting. Rolling Over Often between the second and fifth month, babies learn to roll over. Usually they first roll from front to back. A month later, they usually roll from back to front. It is easier for a baby to lift the head and trunk when on the abdomen than when on the back. deciduous teeth. The first set of teeth, which will later be replaced by permanent teeth. Also called nonpermanent or baby teeth. motor development. The use and control of muscles that direct body movements. gross-motor skills. Being able to use the large muscles to roll over, sit, crawl, stand, and walk. fine-motor skills. Being able to use and control the small muscles, especially those in the fingers and hands. age norm. A range of ages at which average children reach developmental milestones.

4 210 Part 3 Infants Chapter 7 Physical Development of the Infant 211 Sitting Learning to sit takes several months. The baby first must gain strength in the neck and back. The baby must also be able to control the head. 2 months (chin up) 3 months (chest up arm support) Babies can sit briefly with support (being held or with pillows placed at their backs) at three or four months of age. By age seven months, most can sit for a short time without support. For longer periods of sitting, they often 4 months (sits with support) 5 months (sits on lap grasps object) 7-4 This baby can raise his head and chest high for rather long periods of time. Used with permission of Lakeshore Learning Materials, Carson, CA lean forward and support themselves with their arms and legs, 7-5. They may even topple over if distracted. Progress in sitting is rapid in the next few months. By nine months, most babies can sit without support. Leg Control Leg control is the last phase of head-to-foot development. With leg control, locomotion really begins. (Locomotion is the ability to move from place to place.) Babies usually go through the stages of crawling, creeping, standing, and walking. 6 months (sits on high chair, grasps dangling object) 11 months (walks when led) 7 months (sits without support) 8 months (stands with help) 12 months (pulls to stand by furniture) 9 months (stands holding furniture) 14 months (stands alone) 7-3 A baby gains control over the head and neck before the leg muscles. 10 months (creeps) 15 months (walks alone) Ties with Family & Community Visit a child care program that serves infants of various ages. Choose four or five babies who represent different ages. Watch the babies closely and record your observations. Compare the babies abilities to sit, move about, and grasp objects. Share your findings with the class. What do your observations tell you about the way in which infants grow and develop? 7-5 Until back muscles are strong, leaning forward helps babies to sit unaided. American Guidance Service, Inc.

5 212 Part 3 Infants Chapter 7 Physical Development of the Infant 213 Crawling How can you tell when a baby is gaining leg control? When the hands and feet work together smoothly, this shows leg control. Babies play with their own feet and toes at about seven months. They begin to crawl at the same time, 7-6. Babies crawl by pulling with the arms. They do not lift their abdomens from the floor. Creeping Babies may begin creeping between six and eight months. Creeping means to move by using the hands and knees or hands and feet. Babies begin to creep by lifting their abdomens and hips off the floor alternately. The movement may become a rhythmical, rocking motion. Within a couple of months, many babies can move forward or backward on hands and knees (or on hands and feet) with their abdomens off the floor, 7-7. Standing and Walking Six-month-old babies enjoy standing when supported under the arms. They push with their feet and bounce on adults laps. A few months later, babies can pull to a standing position. When babies stand alone, they often enjoy cruising, or walking by holding something for support. At first babies stand with support, holding on to a stable object. As they develop, babies stand further away from objects. They use large objects for balance by holding on with only one of their hands. They also take a few cautious steps between objects and people, 7-8. Most babies first 7-8 With adults ready to catch, a baby who is almost ready to walk will take a few steps. John Shaw 7-6 Playing with toes is a sign of the leg control needed for crawling. 7-7 To creep, this baby must raise the trunk of her body and coordinate the movements of her arms and legs. John Shaw stand alone at between 12 and 14 months and begin walking a few weeks later. Center-to-Extremities Development In center-to-extremities development, control begins with the trunk, then arms, hands, and fingers. This control extends to the hips, then legs, feet, and toes. Children can use their arms and hands to crawl and lift objects before they can use the hand and finger control needed to stack blocks. As you can see, the ability to control the body begins with the center of the body and moves outward. Control of the arms, hands, and fingers develops in stages, 7-9. As you read earlier, the baby comes into the world with a grasping reflex called the Palmar reflex. With this reflex, the baby will automatically grasp whatever is placed in the hand. At two crawl. To move by pulling with the arms but not lifting the abdomen from the floor. creeping. Moving by using the hands and knees or the hands and feet with the abdomen off the floor. cruising. Walking by holding something for support.

6 214 Part 3 Infants Chapter 7 Physical Development of the Infant months No contact 4-5 months Contact only Grasping Ability 5-7 months Hand grasp 9-10 months Superior palm grasp Differences in Physical Development With few exceptions, the order of physical development is the same for every child. However, each child develops at his or her own rate. The rate is affected by heredity, nutrition, illnesses, and activity. Whether a child is praised and encouraged (environment) can also make a difference. Some infants develop more quickly than the age norm; others lag behind. A particular infant may also develop quickly in one area but more slowly in another. If development seems to be much slower than the norms, parents should talk to a doctor. Regular medical care is the best way to find and treat problems that may exist. A doctor, parent educator, or other child development professional might also advise the parents how to best encourage this area of the child s development. voluntary grasping. The intentional grasping of objects months Forefinger grasp 7-9 A baby s grasping ability goes through stages. In the beginning, a baby has a rather clumsy grasp, using the fingers to press an object to the palm. Later the baby can grasp precisely, using the index finger and thumb. Thomas J. Roberts months, babies begin to swipe at objects in an attempt to grasp them. When the baby is about four months, the grasping reflex is replaced by voluntary grasping (the intentional act of grasping of an object). The first grasps are rather crude, but with practice, the baby refines his or her skills. Voluntary grasping is well developed between ages five to six months. At this time, a baby can grasp one object that is handed to him or her months Superior forefinger grasp Six- and seven-month olds usually bring any grasped item directly to the mouth to explore it. At seven months, babies can accept two objects handed to them. A month or two later, babies can use the thumb in opposition to the forefingers to pick up an object. This is the most complex grasp the baby will learn. It is called the pincer grasp. Ten-month-olds can often accept three objects handed to them. Summing It Up A baby s physical development is rapid during the first year. Length and weight increase quickly. The baby s body proportions soon change. The bones begin to develop. Teeth begin to appear in a certain order. Motor development is the ability to control the large and small muscles. Movements using these muscles are called motor skills. Examples include walking; crawling; and using the arms, hands, and fingers. Motor development occurs rapidly in the first year. Control over the body comes in a slow, predictable pattern. Babies reactions to what they see and hear are general at first and then become more specific. Control of the body begins from head to foot and also goes from the trunk outward. There is a sequence to babies motor development. All children develop physically in much the same way. The rate of development may vary because it can be affected by heredity, environment, nutrition, illnesses, and activity. Parents who have concerns about the rate of their child s development should seek a doctor s advice.

7 216 Part 3 Infants Chapter 7 Physical Development of the Infant 217 Reviewing Key Concepts Write your answers on a separate sheet of paper. 1. Most babies (add half, double, triple) their birthweights during the first year. 2. True or false. The rate of growth over the months is more important than the measurement of total growth. 3. True or false. In the first year, the baby gets longer because the legs grow. 4. What are three changes that occur in the bones during development? 5. True or false. Motor development is the way children learn how to play with others and share their toys. 6. True or false. There is a pattern to children s physical development. 7. Which best describes the motor skill development of infants? A. Infants develop the same motor skills at the same time. B. Infants develop rapidly and slowly in the same areas. C. Infants learn at the same rate but the sequence of skills varies. D. Infants learn in the same sequence but the rate varies. 8. The baby gains body control in a certain order. Number the following motor skills in order of occurrence. sits without support with back straight raises the head while on abdomen creeps walks rolls over from front to back stands without help picks up object with thumb used in opposition to finger 9. Reflexes are (learned, unlearned). Voluntary movements are (learned, unlearned). Using Your Knowledge 1. Mathematics. Interview 4 to 6 parents of young children. Ask each parent what the baby s weight and height were at birth, six months, and one year. Record these figures in a master list. Showing your work, figure the average weight and height for this group of babies at each age. How do these figures compare to those given in Figure 7-1? 2. Art. Draw a cartoon featuring an infant who is learning a new fine- or gross-motor skill. Show what the baby might think about gaining this skill and how parents might respond. 3. Child Development/ Communication. As a group or class project, write a one- or two-page brochure that explains at what ages parents can expect their children to learn certain motor skills. You may also find pictures or drawings to illustrate the various skills. The brochure could be checked by a physician before making copies. Find out whether copies could be given to new parents at the hospital, posted in medical offices, or printed in a local newspaper. 4. Child Development/Parenting. Create a homemade toy that would encourage an infant to develop a fine- or gross-motor skill. You can use household items to create the toy, but make sure the toy will be safe and appropriate for use by infants. Demonstrate your toy to the class and explain what skill it would promote. 5. Technology. Work with a partner to visit a Web site designed for parents. Search for information that would help the parents of infants understand their child s physical development in the first year. With your teacher s approval, print out the information. Use the computer to write a review of this information. Based on what you have learned in the chapter, does the advice seem sound to you? Why or why not? Making Observations 1. Observe a doctor giving a wellbaby exam. Ask the doctor to explain each procedure. Note weight and length as well as head and chest measurements. Also note heart and breathing rates and reflexive and voluntary movement. How does the baby s progress compare to age norms? What progress has the baby made since the last checkup? 2. Visit a child care program that serves infants of various ages. Choose four or five babies who represent different ages. Watch the babies closely and record your observations. Compare the babies abilities to sit, move about, and grasp objects. 3. Observe two infants who are the same age. How do they differ in their physical maturity? How do they differ in their motor skills? Does one infant have a lag in maturity or skills? If so, did the parent say anything that explains the lag, such as low birthweight or serious illness? 4. Observe how several babies move toward a toy. Describe exactly how each baby moves toward the toy. (Often babies use more than one motor skill to reach a toy.) Thinking Further 1. Some people believe babies should be fat. Why do some people have this perception? Can such a perception lead to problems? 2. Parents sometimes push their babies to walk early. Can this be harmful to babies? Why or why not? 3. As you read, the grasping reflex is not highly developed until almost one year of age. Does this mean parents can assume their baby is not able to grasp small objects on the floor and insert them into his or her mouth, nose, or ears? Why or why not?