Chapter 8 The First Year
Advances in imaging permit us to understand the anatomic and physiologic correlates of the physical growth, maturation, acquisition of competence, and psychologic reorganization that characterizes infancy and radically change the infant’s behavior and social relationships. Some activities previously thought to be “primitive” or “reflexive” result from complex systems. Swallowing, rather than a simple reflex, results from a complex highly coordinated process involving multiple levels of neural control distributed among several physiologic systems whose nature and relationships mature throughout the 1st year of life. Substantial learning of the basic tools of language (phonology, word segmentation) occurs during infancy. Speech processing in older individuals requires defined and precise neuronal networks; imaging studies have revealed that the infant brain possesses a structural and functional organization similar to that of adults, leading to the belief that structural neurologic processing of speech may guide infants to discover the properties of his or her native language. Myelination of the cortex begins at 8 mo gestation and is nearly complete by age 2 yr; much of this process occurs during infancy. Given the importance of iron and other nutrients in myelination, adequate stores throughout infancy are critical (Chapter 42). Inadequate dietary intake, insufficient interactions with caregivers, or both may alter experience-dependent processes that are critical to brain structure development and function during infancy. Although some of these processes may be delayed, as the periods of plasticity close during the rapid developmental changes occurring in infancy, more permanent deficits may result.
The infant acquires new competences in all developmental domains. The concept of developmental trajectories recognizes that complex skills build on simpler ones; it is also important to realize how development in each domain affects functioning in all of the others. Physical growth parameters and normal ranges for attainable weight, length, and head circumference are found in the Centers for Disease Control and Prevention growth charts (see Figs. 9-1 and 9-2 on the Nelson Textbook of Pediatrics website at www.expertconsult.com 
). Table 8-1 presents an overview of key milestones by domain; Table 8-2 presents similar information arranged by age. Table 8-3 presents age at time of appearance on x-ray of centers of ossification. Parents often seek information about “normal development” during this period and should be directed to reliable sources, including the American Academy of Pediatrics website (www.AAP.org).
Table 8-1 DEVELOPMENTAL MILESTONES IN THE FIRST 2 YR OF LIFE
| MILESTONE | AVERAGE AGE OF ATTAINMENT (MO) | DEVELOPMENTAL IMPLICATIONS |
|---|---|---|
| GROSS MOTOR | ||
| Holds head steady while sitting | 2 | Allows more visual interaction |
| Pulls to sit, with no head lag | 3 | Muscle tone |
| Brings hands together in midline | 3 | Self-discovery of hands |
| Asymmetric tonic neck reflex gone | 4 | Can inspect hands in midline |
| Sits without support | 6 | Increasing exploration |
| Rolls back to stomach | 6.5 | Truncal flexion, risk of falls |
| Walks alone | 12 | Exploration, control of proximity to parents |
| Runs | 16 | Supervision more difficult |
| FINE MOTOR | ||
| Grasps rattle | 3.5 | Object use |
| Reaches for objects | 4 | Visuomotor coordination |
| Palmar grasp gone | 4 | Voluntary release |
| Transfers object hand to hand | 5.5 | Comparison of objects |
| Thumb-finger grasp | 8 | Able to explore small objects |
| Turns pages of book | 12 | Increasing autonomy during book time |
| Scribbles | 13 | Visuomotor coordination |
| Builds tower of 2 cubes | 15 | Uses objects in combination |
| Builds tower of 6 cubes | 22 | Requires visual, gross, and fine motor coordination |
| COMMUNICATION AND LANGUAGE | ||
| Smiles in response to face, voice | 1.5 | More active social participant |
| Monosyllabic babble | 6 | Experimentation with sound, tactile sense |
| Inhibits to “no” | 7 | Response to tone (nonverbal) |
| Follows one-step command with gesture | 7 | Nonverbal communication |
| Follows one-step command without gesture | 10 | Verbal receptive language (e.g., “Give it to me”) |
| Says “mama” or “dada” | 10 | Expressive language |
| Points to objects | 10 | Interactive communication |
| Speaks first real word | 12 | Beginning of labeling |
| Speaks 4-6 words | 15 | Acquisition of object and personal names |
| Speaks 10-15 words | 18 | Acquisition of object and personal names |
| Speaks 2-word sentences (e.g., “Mommy shoe”) | 19 | Beginning grammaticization, corresponds with 50 word vocabulary |
| COGNITIVE | ||
| Stares momentarily at spot where object disappeared | 2 | Lack of object permanence (out of sight, out of mind [e.g., yarn ball dropped]) |
| Stares at own hand | 4 | Self-discovery, cause and effect |
| Bangs 2 cubes | 8 | Active comparison of objects |
| Uncovers toy (after seeing it hidden) | 8 | Object permanence |
| Egocentric symbolic play (e.g., pretends to drink from cup) | 12 | Beginning symbolic thought |
| Uses stick to reach toy | 17 | Able to link actions to solve problems |
| Pretend play with doll (e.g., gives doll bottle) | 17 | Symbolic thought |
Table 8-2 EMERGING PATTERNS OF BEHAVIOR DURING THE 1ST YEAR OF LIFE*
| NEONATAL PERIOD (1ST 4 WK) | |
| Prone: | Lies in flexed attitude; turns head from side to side; head sags on ventral suspension |
| Supine: | Generally flexed and a little stiff |
| Visual: | May fixate face on light in line of vision; “doll’s-eye” movement of eyes on turning of the body |
| Reflex: | Moro response active; stepping and placing reflexes; grasp reflex active |
| Social: | Visual preference for human face |
| AT 1 MO | |
| Prone: | Legs more extended; holds chin up; turns head; head lifted momentarily to plane of body on ventral suspension |
| Supine: | Tonic neck posture predominates; supple and relaxed; head lags when pulled to sitting position |
| Visual: | Watches person; follows moving object |
| Social: | Body movements in cadence with voice of other in social contact; beginning to smile |
| AT 2 MO | |
| Prone: | Raises head slightly farther; head sustained in plane of body on ventral suspension |
| Supine: | Tonic neck posture predominates; head lags when pulled to sitting position |
| Visual: | Follows moving object 180 degrees |
| Social: | Smiles on social contact; listens to voice and coos |
| AT 3 MO | |
| Prone: | Lifts head and chest with arms extended; head above plane of body on ventral suspension |
| Supine: | Tonic neck posture predominates; reaches toward and misses objects; waves at toy |
| Sitting: | Head lag partially compensated when pulled to sitting position; early head control with bobbing motion; back rounded |
| Reflex: | Typical Moro response has not persisted; makes defensive movements or selective withdrawal reactions |
| Social: | Sustained social contact; listens to music; says “aah, ngah” |
| AT 4 MO | |
| Prone: | Lifts head and chest, with head in approximately vertical axis; legs extended |
| Supine: | Symmetric posture predominates, hands in midline; reaches and grasps objects and brings them to mouth |
| Sitting: | No head lag when pulled to sitting position; head steady, tipped forward; enjoys sitting with full truncal support |
| Standing: | When held erect, pushes with feet |
| Adaptive: | Sees pellet, but makes no move to reach for it |
| Social: | Laughs out loud; may show displeasure if social contact is broken; excited at sight of food |
| AT 7 MO | |
| Prone: | Rolls over; pivots; crawls or creep-crawls (Knobloch) |
| Supine: | Lifts head; rolls over; squirms |
| Sitting: | Sits briefly, with support of pelvis; leans forward on hands; back rounded |
| Standing: | May support most of weight; bounces actively |
| Adaptive: | Reaches out for and grasps large object; transfers objects from hand to hand; grasp uses radial palm; rakes at pellet |
| Language: | Forms polysyllabic vowel sounds |
| Social: | Prefers mother; babbles; enjoys mirror; responds to changes in emotional content of social contact |
| AT 10 MO | |
| Sitting: | Sits up alone and indefinitely without support, with back straight |
| Standing: | Pulls to standing position; “cruises” or walks holding on to furniture |
| Motor: | Creeps or crawls |
| Adaptive: | Grasps objects with thumb and forefinger; pokes at things with forefinger; picks up pellet with assisted pincer movement; uncovers hidden toy; attempts to retrieve dropped object; releases object grasped by other person |
| Language: | Repetitive consonant sounds (“mama,” “dada”) |
| Social: | Responds to sound of name; plays peek-a-boo or pat-a-cake; waves bye-bye |
| AT 1 YR | |
| Motor: | Walks with one hand held (48 wk); rises independently, takes several steps (Knobloch) |
| Adaptive: | Picks up pellet with unassisted pincer movement of forefinger and thumb; releases object to other person on request or gesture |
| Language: | Says a few words besides “mama,” “dada” |
| Social: | Plays simple ball game; makes postural adjustment to dressing |
* Data are derived from those of Gesell (as revised by Knobloch), Shirley, Provence, Wolf, Bailey, and others.
