Notes…Infant Physical Development
I. Skeletal system: bones and teeth; skeletal growth refers to the changes in length, weight, and the appearance of teeth.
A. Length and Weight: change rapidly during first year
B. Length is used b/c babies can’t stand to record height
C. Average length at birth: 20 – 21 inches, infants add 9 inches of length, on average, the first year.
D. Babies double their birth weight in 4 – 5 months and triple it in the first year.
E. During the first year, fat tissue appears; in general boys have more muscle length and thickness, girls have more fat.
F. Rate of growth is more important than the actual amounts, it is compared to an average statistic.
G. Failure to Thrive: growth rate slows considerably, indicating a health problem exists. A disease, not enough nutrition, or abuse/neglect are possible causes.
H. With proper care and attention, baby’s health can be restored.
II. Body Proportions differ from those of an adult
A. Infant’s head is ¼ his total length
B. Infant’s forehead is wider than chin, jaw is smaller and slopes back (making it easier to suck)
C. Infant’s head is larger than his chest, by 6 mos. The chest is larger.
D. Infants have a long trunk, “pot-bellied” abdomen and short legs.
III. Bones and Teeth: infant skeleton is made up of mostly cartilage.
A. Their joints bend easily without breaking. Thus, babies can suck their toes but not sit up.
B. Heads can become misshapen from too much time on their backs, so changing infant position during waking hours is recommended.
C. Tummy time encourages development of motor skills like rolling over, reaching, and crawling.
D. Length of bones increase in the first year.
E. Ossification (hardening) occurs in bones.
Pg. 2—Infant Physical Development
F. Number of bones change, like in the hand from 3 (infant) to 28 adult hand bones
G. Deciduous teeth usually appear in a sequence at about 6 months
IV. Motor Development is the use and control of muscles that direct body movements.
A. Gross motor skills: use of large muscles like arms & legs
B. Fine motor skills: use of small muscles like hands & feet
C. Babies move slowly because they must think as they move
D. Babies’ reactions develop from general to specific. Recognition – wiggle develops into smile and reach
E. Motor development occurs from head to foot and from center of the body to extremities.
V. Head to Foot Development begins before birth.
A. Unborn develops a head then arm buds then leg buds.
B. Newborn has well-developed facial muscles for eating compared to leg muscles.
C. Milestones are sequenced steps of development that occur in a constant order
D. Age Norms are ranges of ages at which average children reach developmental milestones
E. When on their tummy babies can lift their heads first, then their heads and chest
F. Babies roll tummy to back then back to tummy
G. Leg control results in locomotion: crawling, creeping, standing and then walking
H. Cruising is walking while holding onto something for support
VI. Center to Extremities: control begins with the trunk, arms, hands and then fingers
A. Palmar reflex gives way to voluntary grasping by 5 to 6 mos.
B. Pincher Grasp use of forefinger and thumb to pickup an object.
Pg. 3—Infant Physical Development
With few exceptions, the order of development is the same for every child. However, children develop at different rates.
The rate of development is affected by heredity, nutrition, illnesses, and activity. Praise and encouragement can affect development as well.
Infants may develop in certain areas quicker than other areas.
If development is slow, medical professionals can find and treat the problem, and/or recommend techniques for parents/caregivers to use to support the developmental process.
3