Growth and developmental changes in the first year of life are numerous and dramatic. Physical growth, matu- ration of body systems, and gross and fine motor skills progress in an orderly and sequential fashion. Though timing may vary from infant to infant, the order in which developmental skills are acquired is consistent. Infants also exhibit vast amounts of learning in the psychosocial and cognitive, language and communication, and social/
emotional domains. Adequate growth and development are indicative of health in the infant or young child.
Nurses must be familiar with normal developmental milestones so that they can accurately assess the infant’s development as well as provide age-appropriate antici- patory guidance to the parents.
Achievement of developmental milestones may be assessed in a variety of ways. While obtaining the health history, the nurse may ask the parent or caregiver if the skill is present and when it was attained. The infant may also demonstrate the skill during the interview or exami- nation, or the nurse may elicit the skill from the infant.
A number of screening tools are also used to assess de- velopment, such as the Denver II Developmental Screen- ing Test (see Appendix G), Prescreening Developmental Questionnaire (PDQ II), Ages and Stages Questionnaire (ASQ), Infant Toddler Checklist for Language and Com- munication, and Infant Development Inventory.
Ill or premature infants may exhibit delayed acquisi- tion of physical growth and developmental skills. When assessing the growth and development of a premature infant, use the infant’s adjusted age to determine ex- pected outcomes. To determine adjusted age, subtract the number of weeks that the infant was premature from the infant’s chronological age. Plot growth parameters and as- sess developmental milestones based on adjusted age. For example, a 6-month-old boy who was born at 28 weeks’
gestation was born 12 weeks early (3 months), so subtract 3 months from his chronological age of 6 months to obtain an adjusted age of 3 months. This infant would demon- strate healthy growth if he were the size of a 3-month-old, and he should be expected to achieve the developmental milestones of a 3-month-old rather than a 6-month-old.
Physical Growth
Ongoing assessments of growth are important so that too-rapid or inadequate growth can be identified early.
With early identification, the cause can be diagnosed and the potential for further appropriate growth maximized.
Infants grow very rapidly over the first 12 months of life.
Weight, length, and head and chest circumference are all indicators of physical growth in the newborn and infant (Table 25.1).
Weight
The average newborn weighs 7 lb 8 oz (3,400 g) at birth.
Newborns lose up to 10% of their body weight over the first 5 days of life. The average newborn then gains about 20 to 30 g per day and regains his or her birthweight by 10 to 14 days of age. Most infants double their birthweight by 4 to 6 months of age and triple their birthweight by the time they are 1 year old (Hagan, Shaw, & Duncan, 2008).
Height
The average newborn is 19 to 21 inches (48 to 53 cm) long at birth. During the first 6 months, length increases
TABLE 25.1 AVERAGE MEASUREMENTS OF INFANTS AT BIRTH AND 6 AND 12 MONTHS
Age Weight Length Head Circumference
Birth 7.5 lb (3,400 g) 19–21 in (48–53 cm) 13–14 in (33–35 cm) 6 months 16 lb (7.3 kg) 25–27 in (63.5–68.5 cm) 16.5–17.5 in (42–44.5 cm) 12 months 23 lb (10.5 kg) 28–30 in (71–76 cm) 17.7–18.7 in (45–47.5 cm)
Adapted from Hagan, J. F., Shaw, J. S., & Duncan, P. M. (Eds.). (2008). Bright futures: Guidelines for health supervision of infants, children, and adolescents (3rd ed., rev.). Elk Grove Village, IL: American Academy of Pediatrics.
C h a p t e r 2 5 Growth and Development of the Newborn and Infant 887 by 1 inch (2.5 cm) per month, then by about a half-inch
per month in the second 6 months (Hagan et al., 2008).
Head and Chest Circumference
Average head circumference of the full-term newborn is 13 to 14 inches (33 to 35 cm). The head circumference is about 1 inch (2 to 3 cm) greater than the chest circum- ference, which averages 12 to 13 inches (30.5 to 33 cm).
The head circumference increases rapidly during the first 6 months: the average increase is about 0.6 inch (1.5 cm) per month. From 6 to 12 months of age, the head circum- ference increases an average of 0.2 inch (0.5 cm) monthly.
The chest circumference is not routinely measured after the newborn period but does increase in size as the child grows (Hagan et al., 2008).
Organ System Maturation
The newborn and infant’s organ systems undergo signifi- cant changes as the infant grows. Systems that undergo significant change include the neurologic system, the car- diovascular system, the respiratory system, the gastrointes- tinal (digestive) system, the renal system, the hematopoietic system, the immunologic system, and the integumentary system.
Neurologic System
The infant experiences tremendous changes in the neu- rologic system over the first year of life. Critical brain growth and continued myelinization of the spinal cord are occurring. Involuntary movement progresses to vol- untary control, and immature vocalizations and crying progress to the ability to speak as a result of maturational changes of the neurologic system.
States of Consciousness
The normal term newborn’s ability to move sequentially through states of consciousness reassures parents and physicians that the neurologic system, though immature, is intact. A normal newborn will ordinarily move through six states of consciousness:
1. Deep sleep: The infant lies quietly without movement.
2. Light sleep: The infant may move a little while sleeping and may startle to noises.
3. Drowsiness: Eyes may close; the infant may be dozing.
4. Quiet alert state: The infant’s eyes are open wide and the body is calm.
5. Active alert state: The infant’s face and body move actively.
6. Crying: The infant cries or screams and the body moves in a disorganized fashion (Brazelton & Nugent, 2011).
Newborns usually progress through these states slowly, rather than going from deep sleep immediately into outright crying.
Brain Growth
The nervous system continues to mature throughout in- fancy, and the increase in head circumference is indica- tive of brain growth. The brain undergoes tremendous growth during the first 2 years of life. By 6 months of age the infant’s brain weighs half that of the adult brain. At age 12 months, the brain has grown considerably, weigh- ing 2½ times what it did at birth. Usually, the anterior fontanel remains open until 12 to 18 months of age to accommodate this rapid brain growth. However, the fon- tanel may close as early as 9 months of age, and this is not of concern in the infant with age-appropriate growth and development.
In general, the neurologic system matures a signifi- cant amount over the first year of life. Myelination of the spinal cord and nerves continues over the first 2 years.
Maturation of the nervous system and continued myelin- ation are necessary for the tremendous developmental skills that are achieved in the first 12 months. During the first few months of life, reflexive behavior is replaced with purposeful action.
Reflexes
Primitive reflexes are subcortical and involve a whole- body response. Selected primitive reflexes present at birth include Moro, root, suck, asymmetric tonic neck, plantar and palmar grasp, step, and Babinski. Except for the Babinski, which disappears around 1 year of age, these primitive reflexes diminish over the first few months of life, giving way to protective reflexes. Protec- tive reflexes (also termed postural responses or reflexes) are gross motor responses related to maintenance of equilibrium. These responses are prerequisites for ap- propriate motor development and remain throughout life once they are established. The protective reflexes include the righting and parachute reactions. Appropri- ate presence and disappearance of primitive reflexes, as well as development of protective reflexes, are indica- tive of a healthy neurologic system. Persistence of primi- tive reflexes beyond the usual age of disappearance may indicate an abnormality of the neurologic system and should be investigated.
Table 25.2 gives descriptions and illustrations of several primitive and protective reflexes, as well as the timing of appearance and disappearance of these reflexes.
888 U N I T 9 Health Promotion of the Growing Child and Family
TABLE 25.2 SELECTED PRIMITIVE AND PROTECTIVE REFLEXES IN INFANCY
Description Age Reflex
Appears Age Reflex Disappears Primitive Reflexes
Root When infant’s cheek is stroked, the infant turns to that
side, searching with mouth. Birth 3 months
Suck Reflexive sucking when nipple or finger is placed in
infant’s mouth Birth 2–5 months
C h a p t e r 2 5 Growth and Development of the Newborn and Infant 889
TABLE 25.2 SELECTED PRIMITIVE AND PROTECTIVE REFLEXES IN INFANCY (continued)
Description Age Reflex
Appears Age Reflex Disappears Moro With sudden extension of the head, the arms abduct and
move upward and the hands form a “C.” Birth 4 months
Asymmetric
tonic neck While lying supine, extremities are extended on the side of the body to which the head is turned and opposite extremities are flexed (also called the “fencing”
position).
Birth 4 months
(continued)
890 U N I T 9 Health Promotion of the Growing Child and Family
TABLE 25.2 SELECTED PRIMITIVE AND PROTECTIVE REFLEXES IN INFANCY (continued)
Description Age Reflex
Appears Age Reflex Disappears Palmar grasp Infant reflexively grasps when palm is touched. Birth 4–6 months
Plantar grasp Infant reflexively grasps with bottom of foot when
pressure is applied to plantar surface. Birth 9 months
C h a p t e r 2 5 Growth and Development of the Newborn and Infant 891 TABLE 25.2 SELECTED PRIMITIVE AND PROTECTIVE REFLEXES IN INFANCY (continued)
Description Age Reflex
Appears Age Reflex Disappears Babinski Stroking along the lateral aspect of the sole and across the
plantar surface results in fanning and hyperextension of the toes.
Birth 12 months
Step With one foot on a flat surface, the infant puts the other
foot down as if to “step.” Birth 4–8 weeks
(continued)
892 U N I T 9 Health Promotion of the Growing Child and Family
TABLE 25.2 SELECTED PRIMITIVE AND PROTECTIVE REFLEXES IN INFANCY (continued)
Description Age Reflex
Appears Age Reflex Disappears Protective Reflexes
Neck righting Neck keeps head in upright position when body is
tilted. 4–6 months Persists
Parachute (sideways) Protective extension with the arms when tilted to the side
in a supported sitting position 6 months Persists
Parachute (forward) Protective extension with the arms when held up in the air and moved forward. The infant reflexively reaches forward to catch himself or herself.
6–7 months Persists
Parachute (backward) Protective extension with the arms when tilted
backward 9–10 months Persists
Adapted from Johns Hopkins Hospital, Arcara, K., & Tschudy, M. (2012). The Harriet Lane handbook (19th ed.).
St. Louis, MO: Mosby.
Respiratory System
The respiratory system continues to mature over the first year of life. The respiratory rate slows from an average of 30 to 60 breaths in the newborn to about 20 to 30 in the 12-month-old. The newborn breathes irregularly, with periodic pauses. As the infant matures, the respiratory pattern becomes more regular and rhythmic.
In comparison with the adult, in the infant:
• The nasal passages are narrower.
• The trachea and chest wall are more compliant.
• The bronchi and bronchioles are shorter and narrower.
• The larynx is more funnel shaped.
• The tongue is larger.
• There are significantly fewer alveoli.
These anatomic differences place the infant at higher risk for respiratory compromise. The respiratory system
does not reach adult levels of maturity until about 7 years of age. The lack of immunoglobulin A (IgA) in the mucosal lining of the upper respiratory tract also con- tributes to the frequent infections that occur in infancy.
Cardiovascular System
The heart doubles in size over the first year of life. As the cardiovascular system matures, the average pulse rate decreases from 120 to 140 in the newborn to about 100 in the 1-year-old. Blood pressure steadily increases over the first 12 months of life, from an average of 60/40 in the newborn to 100/50 in the 12-month-old.
The peripheral capillaries are closer to the surface of the skin, thus making the newborn and young infant more susceptible to heat loss. Over the first year of life, thermoregulation (the body’s ability to stabilize body
C h a p t e r 2 5 Growth and Development of the Newborn and Infant 893 3 months of life and ptyalin is present only in small amounts in the saliva. Gastric digestion occurs as a re- sult of the presence of hydrochloric acid and rennin.
The small intestine is about 270 cm long and grows to the adult length over the first few years of life (Lia- couras, 2011). The stomach capacity is relatively small at birth, holding about one-half to 1 ounce. However, by 1 year of age the stomach can accommodate three full meals and several snacks per day. In the duode- num, three enzymes in particular are important for digestion. Trypsin is available in sufficient quantities for protein digestion after birth. Amylase (needed for complex carbohydrate digestion) and lipase (essen- tial for appropriate fat digestion) are both deficient in the infant and do not reach adult levels until about 5 months of age.
The liver is also immature at birth. The ability to conjugate bilirubin and secrete bile is present after about 2 weeks of age. Conjugation of medications may remain immature over the first year of life. Other functions of the liver, including gluconeogenesis, vitamin storage, and protein metabolism, remain immature during the first year of life.
Stools
The consistency and frequency of stools change over the first year of life. The newborn’s first stools (me- conium) are the result of digestion of amniotic fluid swallowed in utero. They are dark green to black and sticky (Fig. 25.2). In the first few days of life the stools become yellowish or tan. Generally the formula- fed infant has stools the consistency of peanut butter.
Breastfed infants’ stools are usually looser in texture and appear seedy. Newborns may have as many as 8 to 10 stools per day or as few as one stool every day or two. After the newborn period, the number of stools may decrease, and some infants do not have a bowel movement for several days. Infrequent stooling is considered normal if the bowel movement remains soft. Due to the immaturity of the gastrointestinal sys- tem, newborns and young infants often grunt, strain, or cry while attempting to have a bowel movement.
This is not of concern unless the stool is hard and dry. Stool color and texture may change depending on the foods that the infant is ingesting. Iron supplements may cause the stool to appear black or very dark green (AAP, 2012a).
Take Note!
Parents should call the primary care provider if the infant’s stools are red, white, or black; mucuslike; fre- quent and watery; frothy or foul-smelling; or hard, dry, formed, or pelletlike; or if the baby is vomiting.
temperature) becomes more effective: the peripheral cap- illaries constrict in response to a cold environment and dilate in response to heat.
Gastrointestinal System Teeth
Occasionally, an infant is born with one or more teeth (termed natal teeth) or develops teeth in the first 28 days of life (termed neonatal teeth). The presence of natal or neonatal teeth may be associated with other birth anom- alies. The vast majority of newborns do not have teeth at birth, nor do they develop them in the first month of life. On average, the first primary teeth begin to erupt between the ages of 6 and 8 months. The primary teeth (also termed deciduous teeth) are lost later in childhood and will be replaced by the permanent teeth. The gums around the emerging tooth often swell. The lower central incisors are usually the first to appear, followed by the upper central incisors (Fig. 25.1). The average 12-month- old has four to eight teeth.
Digestion
The newborn’s digestive system is not developed fully. Small amounts of saliva are present for the first
UPPER
LOWER Central incisor 8-12 months
Central incisor 8-12 months Lateral incisor 9-13 months
Lateral incisor 9-13 months Cuspid 16-22 months
Cuspid 16-22 months First molar 13-19 months
First molar 13-19 months Second molar 25-33 months
Second molar 25-33 months
FIGURE 25.1 Sequence and average age of tooth eruption.
894 U N I T 9 Health Promotion of the Growing Child and Family
system. Mottling decreases over the first few months of life.
The newborn and young infant’s skin is relatively thinner than that of the adult, with the peripheral capil- laries being closer to the surface. This may cause in- creased absorption of topical medications.
Hematopoietic System
Significant changes in the hematopoietic system oc- cur over the first year of life. At birth, fetal hemoglo- bin (HgbF) is present in large amounts. After birth the production of fetal hemoglobin nearly ceases, and adult hemoglobin (HgbA) is produced in steadily increasing amounts throughout the first 6 months. Since HgbF has a shorter lifespan than HgbA, infants may experience physiologic anemia at age 2 to 3 months (Lerner, 2011).
During the last 3 months of gestation, maternal iron stores are transferred to the fetus. The newborn typically has 0.3 to 0.5 g of iron stores available. As the high he- moglobin concentration of the newborn decreases over the first 2 to 3 months, iron is reclaimed and stored.
These stores may be sufficient for the first 6 to 9 months of life but will become depleted if iron supplementation does not occur.
Take Note!
Maternal iron stores are transferred to the fetus throughout the last trimester of pregnancy. Infants born prematurely miss all or at least a portion of this iron store transfer, placing them at increased risk for iron deficiency ane- mia compared with term infants.
Genitourinary System
In the infant, extracellular fluid (lymph, interstitial fluid, and blood plasma) accounts for about 35% of body weight and intracellular fluid accounts for 40%, compared with the adult quantities of 20% and 40%, re- spectively (Greenbaum, 2011). Thus, the infant is more susceptible to dehydration. Infants urinate frequently and the urine has a relatively low specific gravity. The renal structures are immature and the glomerular fil- tration rate, tubular secretion, and reabsorption as well as renal perfusion are all reduced compared with the adult. The glomeruli reach full maturity by 2 years of age.
Integumentary System
In utero the infant is covered with vernix caseosa, which protects the developing infant’s skin. At birth, the infant may be covered with vernix (earlier gestational age) or vernix may be found in the folds of the skin, axilla, and groin areas (later gestational age). Production of vernix ceases at birth. Fine downy hair (lanugo) covers the body of many newborns. Often this hair is lost over time and is not replaced. Darker-skinned races tend to have more lanugo present at birth than those with light skin.
Acrocyanosis (blueness of the hands and feet) is normal in the newborn; it decreases over the first few days of life (Fig. 25.3). Newborns often experi- ence mottling of the skin (a pink-and-white marbled appearance) because of their immature circulatory
B A
FIGURE 25.2 A. Meconium stool.
B. Typical stool after the first few days.
Note the yellowish, seedy stool of a breastfed infant.
C h a p t e r 2 5 Growth and Development of the Newborn and Infant 895 development of a sense of trust. When the infant’s needs are consistently met, the infant develops this sense of trust. But if the parent or caregiver is inconsistent in meeting the infant’s needs in a timely manner, then the infant develops a sense of mistrust. Table 25.3 lists activi- ties that promote a sense of trust in infancy.
Cognitive Development
The first stage of Jean Piaget’s theory of cognitive devel- opment is referred to as the sensorimotor stage (birth to 2 years) (Piaget, 1969). Infants learn about themselves and the world through their developing sensory and motor capacities. Infants’ development from birth to 1 year of age can be divided into four substages within the sensorimotor stage: reflexes, primary circular reac- tion, secondary circular reaction, and coordination of secondary schemes. Cause and effect guides most of the cognitive development seen in infancy (see Table 25.3).
The concept of object permanence begins to de- velop between 4 and 7 months of age and is solidified by about 8 months of age (Piaget, 1969). If an object is hidden from the infant’s sight, he or she will search for it in the last place it was seen, knowing it still exists. This development of object permanence is essential for the development of self-image. By age 12 months the infant knows he or she is separate from the parent or caregiver.
Self-image is also promoted through the use of mirrors.
By 12 months of age, infants can recognize themselves in the mirror. The 12-month-old will explore objects in different ways, such as throwing, banging, dropping, and shaking. He or she may imitate gestures and knows how to use certain objects correctly (e.g., puts phone to ear, turns up cup to drink, attempts to comb hair) (Piaget, 1969).
Motor Skill Development
Infants exhibit phenomenal increases in their gross and fine motor skills over the first 12 months of life.
Gross Motor Skills
The term “gross motor skills” refers to those that use the large muscles (e.g., head control, rolling, sitting, and walk- ing). Gross motor skills develop in a cephalocaudal fash- ion (from the head to the tail) (Fig. 25.4). In other words, the baby learns to lift the head before learning to roll over and sit (Goldson & Reynolds, 2011). At birth, babies have poor head control and need to have their necks supported when being held. They can lift their heads only slightly while in a prone position. Over the next several months
Immunologic System
Newborns receive large amounts of IgG through the placenta from their mothers. This confers immunity during the first 3 to 6 months of life for antigens to which the mother was previously exposed. Infants then synthesize their own IgG, reaching approximately 60%
of adult levels at age 12 months (Feigin, Cherry, Kaplan,
& Demmler-Harrison, 2009). IgM is produced in sig- nificant amounts after birth, reaching adult levels by 9 months of age. IgA, IgD, and IgE production increases very gradually, maturing in early childhood (Feigin et al., 2009).
Psychosocial Development
Erik Erikson (1963) identifies the psychosocial crisis of infancy as Trust versus Mistrust. Development of a sense of trust is crucial in the first year, as it serves as the foun- dation for later psychosocial tasks. The parent or primary caregiver can have a significant impact on the infant’s
A
B
FIGURE 25.3 A. Acrocyanosis. Note blueness of the hands.
B. Mottling of the skin in a young infant.