PostnatalGrowth & Maturation

Growth & Maturation

GROWTH– Increase in size of tissue or organ

Hypertrophy– Auxetic – increased cell size– Accretionary – increased extracellular constituents

Hyperplasia– Multiplicative – increased cell number

MATURATION– Change in structure or function of the tissue or organ

moving it closer towards the mature state

Methods of Studying Growth

Longitudinal Study– one or more individuals are monitored over several

years– time consuming, costly, attrition of sample– only way to study the dynamics of growth

Cross-Sectional Study– sample many different children at same time– good for norms and bench marks

Count Philibert de Montbeillard

Measured son every 6 months from birth to 18 years

(1759-1777)

Standards for Growth Assessment

What are the appropriate criteria for choice?– Cross-sectional / longitudinal– Local / National / International– Special populations

What is available?

NCHS/CDC Growth Charts

The most commonly used norms in North America are cross-sectional norms produced in 1977 by the National Center for Health Statistics.

These were recently updated and are now presented by the Center for Disease Control (2000)

CDC Growth Charts

Height for Age & Weight for Age

Weight for Height

BMI for Age

EARLYLATE

Comparison of early and a late maturers who attain similar height at age 17yrs

Longitudinal vs Crossectional

CDC Growth Charts All Racial and Ethnic Groups Combined

• Environmental influences appear to contribute to variations in growth more than genetic influences

• Inadequate sample data for racial- and ethnic-specific charts

• The effect of race and ethnicity on BMI-for- age is unclear

Anthropometric Assessment of Special Populations

A Special Population is one that can not be assessed by orthodox methodology

Growth & Nutritional Status assessments

Treatment and Rehabilitation of Treatment and Rehabilitation of Children with cerebral palsy, Children with cerebral palsy, brain injuries and other brain injuries and other neuromotor problemsneuromotor problems

S.H.A.P.E.S.

SELECTED MEASUREMENTS & EQUIPMENT

ANTHROPOMETRICMEASUREMENTS

MEASUREMENTEQUIPMENT

weight wheelchair scale or portablebeam-type balance scale

stretch stature or recumbentlength

stadiometer or recumbentboard

segment lengths - upper armand lower leg

modified segmometer

girths - head, relaxed armand calf

anthropometric metal tape

skinfolds - triceps,abdominal and medial calf

Slim Guide skinfold caliper

S.H.A.P.E.S. custom software– serial plotting (up to 100 measurement occasions)– anthropometric profile

Height Distance & Velocity Curves

Adolescent growth spurt growth most rapid in first two years

DISTANCE CURVE

VELOCITY CURVE

Height Velocity Curves

Indicator of maturity

Needs longitudinal data

Other “systems” have similar curves

Shifting of age axis values to coincident age of PHV before averaging velocity curves

Means of PHV Parameters

Age at takeoff – ♀: 8.5 - 10.3 yrs ♂: 10.3 - 12.1

yrsAge at PHV

– ♀: 11.4 - 12.2 yrs ♂: 13.4 - 14.4 yrsPHV (cm/yr)

– ♀: 7.0 - 9.1 yrs ♂: 8.2 - 10.3 yrs

Intrauterine growth velocity is greater than during any postnatal period.

Timing of birth affects growth velocities

Predicting Adult Size

Predictions of adult stature can be made from:– heights at earlier age– parental stature– skeletal maturation

Four Curves of

Growth

Differential GrowthBirth to Maturity

30-40 times– Muscle, Genital Organs

20-25 times– Body, Skeleton, Respiratory System

15-20 times– heart, Liver

< 5 times– Nervous System

Head Circumference for Age

Shape Changes with Age

Changes in Proportions

Somatotype

Sheldon vs Heath-Carter Shape vs Size Mainly used as photographic record of child

Adult Size not well correlated with Birth Size

Adult proportions are a result of complex genetic and environmental influences

Differential Growth

Mean Ages (yrs) at Peak Velocity

Girls (n=10) Boys (n=12)

Leg Length 11.3 13.4

Stature 11.8 14.1

Sitting Height 12.4 14.6

Humerus Width 11.9 14.1

Tibia Width 11.1 13.6

39

Table 4-1: Indication(●) of when peak size velocity of each measurement is expected to occur in relation to Peak Height Velocity (PHV)

Before PHV

After PHV

Weight ●

Sitting Height ●

Leg Length ●

Shoulder Width ●

Elbow Width ●

Knee Width ●

Arm Girth ●

Thigh Girth ●

Adult Sexual Dimorphism

No difference in proportional weightMale-Female difference greatest in: Triceps, Biceps, Front Thigh and Medial Calf Skinfolds Secondary sexual adiposity

Adult Sexual Dimorphism

Estimates of Muscularity

Skinfold-Adjusted Arm Girth – Muscularity Indicator

G

Ga = G - (3.14xS)

S = Skinfold ThicknessG = GirthGa = Skinfold adjusted Girth

Ga

SG

Girth adjusted for Skinfold at that site

Girth Skinfold

s.a. Arm girth Relaxed Arm Girth Triceps

s.a. Chest girth Chest Subscapular

s.a. Thigh girth Thigh Front Thigh

s.a. Calf girth Calf Medial Calf

s.a. Forearm girth Maximum Forearm Forearm

s.a. Girth (cm) = Girth (cm) - (Π x Skinfold (mm) / 10)

Adult Sexual Dimorphism

s.a. Girths are Muscularity indicators

Greatest differences between the sexes in the upper body

Greatest potential for hypertrophy in the upper body

Muscularity profile is very sensitive to the specific activity of the individual

Adult Sexual Dimorphism

Proportionally larger sitting height in females

Males tend to have proportionally longer limbs.

Biggest difference in distal segments

Adult Sexual Dimorphism

Humerus to Femur Width differences reflects muscularity differences

Males have broader and deeper chests proportionally.

Classic hip-shoulder dimorphism:

Males proportionally wider shoulders

Females have proportionally wider hips

Shoulder-Hip Dimorphism

48

  Sex N MeanStd.

Deviation

Biacromial/Biiliocristal Breadth Male 69 1.44 0.12

  Female 115 1.31 0.12

49

2D:4D Ratio(2nd digit length to 4th digit length ratio)

Sex N Mean Std. Deviation

Male 136 0.947 0.029

Female 137 0.965 0.026

2D 4D

a Allison A. Bailey, Peter L. Hurda, Department of Psychology, University of Alberta. 2004

2D:4D Ratio

Ratio determined in utero– 2D:4D is negatively correlated with prenatal testosterone and

positively correlated with prenatal estrogen

Larger ratio in females– Married women had higher 2D:4D ratios than unmarried

women– Significant negative associations were found between 2D:4D

in men and reproductive success and significant positive relationships between 2D:4D in women and reproductive success

Found to be related to:– Aggression, Competitive success, Sexual orientation

51

Histogram of Both Sexes Combined

Sex N Mean S.D.

Male 76 0.975 0.037 Female 66 0.994 0.043

Gradient vs Indicator Maturity Gradients

– assessment of the relative rates of development of parts or structures of the body

Maturity Indicators– Some characteristic of the body that has distinct

stages of development that all normally developing children will pass through

Maturity Gradient

54Upper Arm Maturity Gradient

Three 13 year old Girls

Three 14 year old Boys

Bigness vs Maturity

Do not confuse size with maturationObesity often associated with

advanced maturation skeletally but not in muscular development

Maturity Indicators

Age of Peak Height VelocitySkeletal AgeDental AgeMenarcheSecondary Sexual Characteristics

Skeletal Age

Closer relationship of Age at Menarche with Skeletal Age (SA) than Chronological Age (CA)

Stages of Penis Development

Stages of Pubic Hair Development (Girls)

Synchrony of Pubertal Events

Synchrony of Pubertal Events

Maturity Indicator Intercorrelations