2. Physical Development of the Infant8
Physical Development of the Infant 2

3. Key Terms 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

4. Objective
Describe how an infant develops physically during the first year.

5. Skeletal Growth Skeletal system is made up of bones and teeth Length
increase birth length by 30% during first five months
reach 1.5 times their birth length during first year
boys are usually ¾ inch longer than girls by one year of age
continued

6. Skeletal Growth Weight
around 9 months, babies are rather chubby as fat tissues increase
boys are usually 1½ pounds heavier than girls by one year of age
boys have more muscle mass than girls
girls have more fat than boys
continued

7. Skeletal Growth Average length and weight during first year
Age in Months
Length
Weight
Birth
20 in.
7½ lbs. 3
23¾ in.
12½ lbs. 6
26 in.
26¾ lbs. 9
28 in.
20 lbs. 12
29½ in.
22¼ lbs.
continued

8. Skeletal Growth
Failure to thrive is a condition in which a child fails to grow at a healthy rate
Possible causes
disease preventing nutrient absorption
food not providing enough nutrients
feedings offered too infrequently or last too short of a time
baby abused or neglected
continued

9. Skeletal Growth
Body proportions (relative size of body parts) differ from those of adults
infant’s head one-fourth of total length; adult’s head one-eighth of total height
Head larger than chest
“Pot-bellied” abdomen and short legs
Center of gravity high on baby’s body
continued

10. Skeletal Growth Infant skeleton is mainly made of cartilage
large spaces between “bones” to help the joints bend easily without breaking
skeletons are not sturdy, which makes sitting and standing impossible
bones can easily become misshapen
continued

11. Skeletal Growth Babies need to change position often
tummy time encourages rolling over, reaching, crawling
continued

12. Skeletal Growth
During the first year, three changes occur in a baby’s bones
length increases
ossification (depositing of the minerals, calcium, and phosphorus) begins
number of bones changes
few bones in hand differentiate into many
parts of skull become one large bone
continued

13. Skeletal Growth
Deciduous teeth (nonpermanent) appear in a predictable manner, but timing varies greatly
most babies begin cutting teeth during second half of first year

14. What Do You Think?
How should families care for an infant’s deciduous teeth?
Why is it important to practice healthy dental hygiene for teeth that will be replaced by permanent teeth at a later date?

15. Objective
Describe the order in which an infant’s motor skills develop.

16. Motor Development
Motor development is the use and control of muscles that direct body movements
Gross-motor skills use large muscles
trunk, arms, legs
Fine-motor skills use small muscles
hands, fingers
continued

17. Motor Development Baby’s motor skills develop in three main patterns
movements are slow because babies must think as they move
reactions develop from general to specific
development occurs in two directions
head-to-foot
center-to-extremities

18. Head-to-Foot Development
Begins before birth
Milestones are sequenced steps
order of steps more constant than timing
Age norm is a typical time when a developmental milestone occurs
can be expressed as an average age or age range
continued

19. Head-to-Foot Development
continued

20. Head-to-Foot Development
Crawl means to move by pulling with arms, not lifting abdomen from floor
about seven months
Creeping means to move by using hands and knees or feet
between six and eight months
Cruising means to walk by holding something for support
between 12 and 14 months

21. Center-to-Extremities Development
continued

22. Center-to-Extremities Development
Control of arms, hands, fingers develop in stages
born with Palmar reflex
at two months, begin to swipe at objects in an attempt to grasp them
about four months, grasping reflex is replaced by voluntary grasping
well developed between five to six months
at eight or nine months, pincer grasp is developed

23. What Do You Think?
How can adult caregivers support head-to-foot development and center-to-extremities development of infants? Describe some specific activities that can be incorporated into the infant’s daily schedule.

24. Glossary of Key Terms
age norm. Typical time when a developmental milestone, such as walking or talking, occurs; an age norm can be expressed as an average age or an age range.
body proportions. Relative size of body parts.
crawl. Moving by pulling with the arms, but not lifting the abdomen from the floor.

25. Glossary of Key Terms
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.
deciduous teeth. First set of teeth, which will later be replaced by permanent teeth; also called nonpermanent or baby teeth.

26. Glossary of Key Terms
failure to thrive. Condition in which a child fails to grow at a healthy rate.
fine-motor skills. Being able to use and control the small muscles, especially those in the fingers and hands.
gross-motor skills. Being able to use the large muscles to roll over, sit, crawl, stand, and walk.

27. Glossary of Key Terms
motor development. Use and control of muscles that direct body movements.
ossification. Hardening of bones caused by the depositing of the minerals calcium and phosphorus.
skeletal system. Body system that includes the bones and teeth.
voluntary grasping. Intentional grasping of objects.