Prenatal and Infant Growth ©Gallahue, D.L., Ozmun, J.C., Goodway, J.D. (2012). Understanding Motor Development. Boston: McGraw-Hill. McGraw-Hill/Irwin © 2012 McGraw-Hill Companies. All Rights Reserved.
6-2 The rate of growth from conception through infancy is unsurpassed throughout the rest of life.
6-3 Zygotic Period : Conception – 1 st week Diameter = 2.5mm.(0.01in.) 50% spontaneously abort Embryonic Period : 2 nd week – 2 nd month Ectoderm/mesoderm/endoderm (table 6.1) Differentiation (figure 6.1) At-risk for congenital malformations
6-4 Early Fetal Period: 3 rd – 6 th month Rapid growth period 4 th month most rapid Doubles wt. (4oz/113g) & length (6-8in/15- 20cm) Lanugo : Fine hair covering Vernix Caseosa : Fatty jell protection Structurally complete; functionally immature by end of 6 th month; age of viability
6-5 Later Fetal Period: 7 th -9 th month Weight triples (table 6.2) Lanugo & Vernix fluid disappear 7 th month is a quiet period 8 th -9 th months more activity Normal gestation: weeks Typical full term newborn length: in (48-53 cm) weight: 6-8lbs (3-4kg)
6-6 Neonatal Period : Birth-4 weeks Body proportions (figure 6.2) Body weight: Males 4%> females Potential for catch-up growth among LBW, VLBW & ELBW infants (see: Developmental Dilemma ) Early Infancy: 4 weeks-1 year Rapid gains in height & weight Weight triples by end of 1 st year Length increases to about 30 in (76cm) by 1 st birthday
6-7 Later Infancy: 12 months – 24 months Growth: Rapid but slower than 1 st year Dimensions at 2 nd birthday: Girls: Length= 34in (86cm); weight = 26lbs (12kg) Boys: Length = 35in (89cm); weight = 28lbs (12.7kg) Correlation:.60 between height & weight an uneven process of developmental direction process WHO vs. CDC Growth charts: ( see: International Perspectives ) Girls: (figures 6.3) Boys: (figure 6.4)
6-8 Growth during infancy is a rapid but uneven process influenced by the principles of proximodistal and cephalocaudal development.