Postnatal Growth & 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 ( )

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

EARLY LATE 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

Caribbean Growth Data n =1697

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 Children with cerebral palsy, brain injuries and other neuromotor problems

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

SELECTED MEASUREMENTS & EQUIPMENT

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

Height distance and velocity curves for three subjects from Saskatchewan Growth Study

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 – ♀: yrs♂: yrs Age at PHV – ♀: yrs ♂: yrs PHV (cm/yr) – ♀: yrs ♂: 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 Growth Birth to Maturity times – Muscle, Genital Organs times – Body, Skeleton, Respiratory System 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 Stature Sitting Height Humerus Width Tibia Width

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Adult Sexual Dimorphism No difference in proportional weight Male-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 Thickness G = Girth Ga = Skinfold adjusted Girth Ga S G

Girth adjusted for Skinfold at that site GirthSkinfold s.a. Arm girthRelaxed Arm GirthTriceps s.a. Chest girthChestSubscapular s.a. Thigh girthThighFront Thigh s.a. Calf girthCalfMedial Calf s.a. Forearm girthMaximum ForearmForearm 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 51 SexNMean Std. Deviation Biacromial/Biiliocristal BreadthMale Female

52 2D:4D Ratio (2 nd digit length to 4 th digit length ratio) SexNMeanStd. Deviation Male Female D 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

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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

57 Upper Arm Maturity Gradient

Three 13 year old Girls

Three 14 year old Boys

Bigness vs Maturity Do not confuse size with maturation Obesity often associated with advanced maturation skeletally but not in muscular development

Maturity Indicators Age of Peak Height Velocity Skeletal Age Dental Age Menarche Secondary 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)

Maturity Indicator Intercorrelations

Synchrony of Pubertal Events