Proportional changes (*See Table 10-1)
Growth is very rapid in the initial 6 months
Infants gain 150 to 210 grams weekly until approx. 5-6 mos., when the birth weight has doubled
Weight gain slows during the second 6 mos.
By 1 yr of age, birth weight has tripled
Infants who are breastfed beyond 4-6 mos. of age typically gain less weight than bottlefed infants
Breastfed infants tend to self-regulate energy intake
Height
increases by 2.5cm (1in.) a month during the first 6 mos. of life slows down during the second 6 mos.
Increases in length occur in spurts, rather than a slow, gradual pattern
By 1 year of age, length has increased by 50%; occurs mainly in the trunk
Head growth is rapid- reflects growth & differentiation of the nervous system increases approx.. 1.5cm/ month for 1st 6 mos. declines to 0.5cm/mo for 2nd 6 mos.
Posterior fontanel closes by 6-8 wks.; anterior fontanel closes by 12-18 mos.
Chest assumes a more adult contour, with the lateral diameter becoming larger than the anteroposterior diameter
Heart grows less rapidly than rest of body
Maturation of Systems (*See Table 10-1)
Respiratory rate slows and is relatively stable; respiratory movements are abdominal
Close proximity of trachea to bronchi and its branching structures transmits infectious agents easily
Short, straight Eustachian tube allows infection to ascend from pharynx to the middle ear.
Inability of immune system to produce IgA in mucosal lining provides less protection for infants against infection
Heart rate slows; systolic pressure rises during 1st 2 mos; diastolic pressure decreases during 1st 3 mos.
Fetal hemoglobin present for 1st 5 mos.- a common result at 2-3 mos of age is physiologic anemia
Maternally derived iron stores present for 1st 5-6 mos.= accounts for lowered hemoglobin levels at age 6 mos.
Digestive processes relatively immature at birth; majority of it do not begin functioning until