Early Childhood Development SHH 278 December 3, 2007

Early Childhood Development

SHH 278December 3, 2007

Core Concepts Human development is shaped by a

dynamic and continuous interaction between biology and experience (transactional model).

Culture influences every aspect of human development

Self-regulation is cornerstone of development and cuts across all domains

Core Concepts, contin. Children are active participants in

their own development Human relationships are building

blocks The broad range of individual

differences makes the distinction between normal variation, transient delays and permanent impairment difficult

Core Concepts, contin. Individual pathways of

development are characterized by continuities and discontinuities

Human development is shaped by an interplay between vulnerability and resilience

The timing of experience can matter, but the developing child is plastic

Core Concepts, contin.

The course of development in early childhood can be altered by effective interventions (coming event).

Phases of Brain Development (Last trimester-first year)

Neurulation and neurogenesis Migration Neuronal differentiation and

pathfinding Synaptogenesis Maturation and pruning Gliagenesis or myelination

The Messengers Information is carried across synapses

and along nerves by chemicals. Receptors on neurons are specific to the

chemical The number of receptors may reflect

experience Neural growth factors may also reflect

experience, and affect structure of the brain

These messengers are also affected by events elsewhere in the body

Negative Effects on Developing Brain

Effects depend on timing of exposure

Much of development occurs very early before the pregnancy may be recognized

Some substances may be more toxic to the fetus than the infant (blood-brain barrier)

Sources of Damage Single gene conditions

Altered brain structure Build up of natural metabolites

Multigenic conditions Chromosomal abnormalities Prenatal infection (TORCHeS) Prenatal heavy metal exposure

(Pb, Hg, Al)

Sources, contin. Substance Use

Alcohol Tobacco Cocaine

Other environmental exposure (PCBs) Chronic stress Nutrient Deficiencies (Fe-deficiency in

infancy) Post-natal infection

Domains of Development Attention (Selectivity, persistence,

inhibitory control) Language Everyday Cognition (schemata, scripts) Intelligence Reading and Spelling Theory of mind (understanding others,

beliefs, deceptions, read expressions)

Domains, contin.

Morality/Character development Gender Attachment Emotional Development Peer Relations Sleeping and Feeding (state

regulation) Physical growth/development

Environmental Influences on Development Characteristics of the individual

(temperament, physical appearance)

Family (structure, relationships, stress and change in families, sibship and birth order)

School (climate, organization) Culture/Community (social class,

neighborhood, media)

Pathways for Environmental Effects on Neurodevelopment

Parental Processes


Parental Processes Parental physical and emotional

health Provision of stimulating experiences

in the home Parental sensitivity Parental harshness

Disruptions of Parental Processes

Maternal depression Child maltreatment and neglect Parental loss Lack of resources (education,

income, inadequate day care, substance use


Parental Processes Neighborhood Processes

Neighborhood Processes

Resources for Parents Relationships Norms or Collective Efficacy Evidence is limited

Observational studies show minor effects

Moving to Opportunity


Parental Processes Neighborhood Processes Child Care Processes

Disruptions of Care Processes

Poor quality care Emergence of negative

development

Consideration of Physical Growth and Health

Physical growth Height Weight for Height

Acute illness Resilience Vulnerability

Physical Health, contin.

Chronic illness Drug side effects Absenteeism Limitations in daily activities Effects of symptoms (chronic otitis)

Case Study

Low Birth Weight

Mean Total IQ by Birthweight

38

58

78

98

118

138

Mea

n (S

td. D

ev.)

IQ

Total IQ

<=1000 gr 1001-1500 gr 1501-2500 gr >2500 gr

n=179 n=280 n=132 n=97

Risk of Behavioral Problems Score >14 by BWTOdds Ratio & Confidence Intervals

0.0 1.00 2.00 3.00

<=1000 gr

1001-1500 gr

1501-2500 gr

>2500 gr **

**

What is LBW? What does it signify?

Low Birth Weight Shortened gestation-true risk for fetal

immaturity Low weight for given duration of

gestation IUGR-intrauterine growth restriction

Obstetric diagnosis based on serial ultrasound SGA-Small for gestational age

Pediatric diagnosis from fetal growth charts Combines pathological lbw with constitutionally

small

What is being measured Risk for infant mortality (and

morbidity) “Too small; too soon”

Birth weight Duration of pregnancy

Early definition Yllpo: in 1930s-“risk” = <=2500 grams Based on inflection point in bwt

distribution, not much empiricism

Evolution of definitions

WHO 1948 Immature=<=2500 grams Premature= <37 completed weeks of

gestation WHO 1961

Low birth weight= <=2500 grams Premature=<37 weeks

Further Definitions

Birth weight Low birth weight= <2500 grams (5.5

lbs) Very low birth weight = <1500 grams

(3.3 lbs.) Extremely low birth weight = <1000

grams (2.2 lbs) Confounds duration of pregnancy

with adequacy of weight gain

Target Construct for Measurement

“Fetal maturity” Fetal development is sufficient for

extra-uterine life Variations in organ maturity even for a

given gestational age 38-42 weeks optimal for this transition

for most infants Gestational age is preferred measure

More Definitions

Extreme prematurity <28 weeks Moderately preterm 30 or 32-36

wks Late premature 36 weeks Term 37-41 completed weeks

Measures, contin.

Duration of gestation <37 weeks Last menstrual period (LMP) Ultrasound before 20 weeks Biophysical profile Fetal lung maturity Physiologic severity measures Postnatal physical examination

Biological Factors influencing birth weight

Constitutional low weight Duration of gestation Congenital malformations Toxic exposures (smoking) Defects of placentation Complications of pregnancy Multiple gestation

Percentage of Preterm Births-US Births

9.5

10

10.5

11

11.5

12

12.5

1990 1993 1995 1997 1999 2000 2004

% PT

Demographic Factors Increasing the Risk of Prematurity

Maternal age at the extremes of reproductive span

Race/ethnicity Poverty Multiple births

Why is Prematurity/Low Birth Weight a Problem?

Mortality

Significance of Cut Points

“Risk factors” Cut points should be biologically

meaningful Do cut points in birth

weight/gestational age have meaning for mortality?

Infant mortality by birth weight

1

10

100

1000

<50

0 g

500-

999

1000

-149

9

2000

-249

9

2500

-299

9

3000

-449

9

5000

+

IMR(2002)

Infant Mortality by Gestational Age

0

50

100

150

200

250

300

350

400

450

<28 wks 28-31 32-35 36 37-41

IMR

Mortality by Gestational Age, 1986/87-1996/96

0

10

20

30

40

50

60

70

80

90

<23 24 25 26 27

1986/871995/96

Hack, 1991; Lemons, 2001

Significance of Birth Weight Cut Points Traditional cut-points do not signal

biological break points Effects of changes in birth weight

A unit increase in birth weight does not equally affect mortality at different gestational ages

Even for given gestational age/birth weight, other factors may influence outcome

Intrauterine events

Complications of pregnancy, especially those associated with IUGR constitute fetal stressors

Response to stress Accelerated maturation Fetal programming


Mortality Morbidity

Neurodevelopmental Morbidity related to prematurity

What? How?

Survival With Major Morbidity

0

10

20

30

40

50

60

501-750 751-1000 1001-1250 1251-1500

19911996

Lemons, et al, 2001

0

5

10

15

20

25

30

35

40

45

Pe

rce

nta

ge

of E

ach

Birt

h W

eig

ht G

rou

p

<=1000 gr

1001-1500 gr

1501-2500 gr

>2500 gr

Type of Specific Conditions Reported

Asthma Neuro-Seq Sens-Neur L.D. Int CNS Cond

by Birth Weight

Specific Conditions/Limits in ADLPercentage of Each Birth Weight Group

0%10%20%30%40%50%60%70%80%90%

100%

<=1000 1001-1500gr

1501-2500gr

>2500 gr

Percent

DisSpec CondNeither


Mortality Morbidity Physical Growth

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

0 1 5 7 12 14 17 19 23 26 28 33 37 45 50 57

Birthweight (kg)

Mea

n h

t/ag

e Z

sco

re 1.00-1.49

1.50-1.99

2.00-2.49

2.50-2.99

3.00-3.49

3.50-3.99

4.00-4.49

4.50-4.99

Physical Growth/Weight

Mean weight-for-age Z scores by 500-g birth weight category and by 3-mo age groupings for children <36 mos of age and 6-mo groupings for children 36 to 59 mos of age based on Tennessee Linked Special Supplemental Food Programs for Women, Infants and Children and birth certificate records, 1975-1985.

Binkin, 1988

Age (Mo)

Physical Growth/Height

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

0 1 5 7 10 13 16 19 23 25 28 33 39 45 50 57

Birthweight (kg)M

ean

ht/a

ge Z

sco

re

1.00-1.49

1.50-1.99

2.00-2.49

2.50-2.99

3.00-3.49

3.50-3.99

4.00-4.49

4.50-4.99

Mean height-for-age Z scores by 500-g birth weight category and by 3-mo age groupings for children <36 mos of age and 6-mo groupings for children 36 to 59 mos of age based on Tennessee-Linked Special Supplemental Food Programs for Women, Infants and Children and birth certificate records, 1975-1985.

Age (Mo)


Mortality Morbidity Physical Growth Cognitive/Emotional Development

Total IQ by BirthweightPercent with IQ <70 and 70-85

05

1015

202530

3540

4550

<=1000 gr 1001-1500 gr 1501-2500 gr >2500 gr

Percent

<70 70-85n=179

n=280n=132

n=97

Percentage with School Difficulties by Birthweight

0

10

20

30

40

50

60

<1000 1000-1499 1500-2499 2500+

OthRep+OthRep

Factors Affecting Morbidity/Development

Neonatal Events

Considering Covariates

Phys. Soc/Emot.Cogn.Hlth. Devel.

Devel.Neonat. + - +SES + +/- ++Mat PhysHlth + - -Mat MentHlth - ++ -

Perinatal and Neonatal Events

Hospital of birth/NICU care Variations in obstetric management Volume-outcome relationships Inter-NICU variability in management

lead to variations in mortality

Site variation* in %CP

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12

% CP

NICHD Neonatal Network, *adjusted for demographics and antenatal interventions

Site variation* in %MD1<70

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12

% MDI<70

NICHD Neonatal Network, *adjusted for demographics and antenatal interventions

Factors Affecting Morbidity/Development

Neonatal Events Post-natal Environment

Longer Term Outcomes

Adolescence/young adulthood Reproduction

Summary

Early childhood development is complex, affected by a variety of preconceptional, prenatal, perinatal, neonatal and post-natal events

Many “risk factors” (e.g. low birth weight) are relatively static and do capture this complexity

Summary-2

Need more specific models of developmental trajectories combining biologic and environmental factors

Need more dynamic risk assessment models

Need to incorporate health into the model


Parental Processes Neighborhood Processes Child Care Processes ?Health Care Processes

Documents

Early Childhood Development SHH 278 December 3, 2007