Prenatal, Birth, and Postnatal Periods

moment of conception fixes your genetic make-up

BUT, from that moment, a single cell begins to adapt to its environment. Within 9 mos. increases in size two hundred billion times!

Transaction between special organism◦ Zygote - a single-cell fertilized ovum◦ Unique genetic code

Specialized Environment ◦ Species Typical

Fertilization in fallopian tube (oviduct) Implantation in uterus

At birth- billions of specialized cells capable of surviving in complex environment

Ovum-Germinal Period◦ ~ 2 - 14 days (travel)

Embryonic Period◦ ~2 -8 weeks (implantation)

Fetal Period◦ 8 -38 weeks (major development)

Starts as Zygote in fallopian tube Mitosis produces duplication of cells 32 cell ball called morula Blastula (Blastocyst) differentiates into:

◦ Embryoblast (Inner cell mass) – develops into the embryo

◦ Trophoblast (Outer protective layer) Becomes amnion, chorio, placenta, allantois (umbilical

cord)◦ Ends at implantation in the uterus wall

Duplication of undifferentiated cells As cellular reproduction continues,

differentiation begins By the time it enters uterus, two distinct

masses have formed

Embryoblast ◦ Inner cell mass ◦ becomes the embryo

Trophoblast◦ Outer layer of cells◦ becomes

fetal membranes amnion chorion allantois

Blastula (or blastocyst)- the embryoblast & trophoblast

Hormones prepare uterine environment Blastula sends out tendrils

Marks end of Germinal Period

Marks the beginning of Embryonic Period

Endoderm◦ Innermost◦ Becomes digestive, respiratory, internal organs

(pancreas & liver) Mesoderm

◦ Center Layer◦ Muscles, bones, circ. system

Ectoderm◦ Outermost◦ Hair, Skin, CNS

Starts when all basic structures are complete

Period of refinement for survival in outside world

Cephalo-caudal◦ Head - tail (foot)

Proximo-distal ◦ Near-far

Gross - fine◦ basic - refined

Substances or agents present prenatally that cause physical or psychological abnormalities

Laws of developmental direction mean that timing is important

Generally speaking, those having effects during embryonic development will have greater harmful outcomes

Maternal Diseases Drugs Environmental Hazards Maternal Characteristics

◦Toxoplasmosis potentially serious disease caused by parasite in

undercooked meat and cat feces• Passed to fetus through the placenta• Possible Fetal Complications:

Visual defects & Blindness Hearing Loss Mental Retardation Seizures Cerebral Defects Low Birth Weight

◦Cytomegalovirus (CMV) Caused by type of herpes virus

• Passed to fetus as it passes through birth canal of infected mother or through the breast feeding

• Possible fetal complications (which may appear for the next few years): Mental Retardation Hearing Loss Microcephaly

◦Rubella Caused by a flu-like virus so damaging to the fetus during the first 16 weeks of

pregnancy that universal immunization is crucial• Passed to the fetus through the placenta• Possible fetal complications: (during first 16 weeks after

conception): Visual Defects / Blindness Hearing Loss / Deafness Cardiovascular Defects Neurological Defects (including AUTISTIC SYMPTOMS!) growth retardation

◦Genital Herpes viral infection caused by the herpes simplex virus remains in nerve cells causing periodic recurrences

• Passed to the fetus in 3 ways: 1) through the uterus 2) passing through the birth canal 3) immediately after birth

• Possible fetal complications: Visual Defects / Blindness Cerebral Defects

Cigarette Smoking• Increases chances of:

ectopic pregnancy or miscarriage Low birth weight babies (< 5.5 lbs) results from

pre-term delivery and/or poor intrauterine growth • Increased risk of chronic disabilities (e.g., cerebral

palsy, mental retardation, learning problems)

Alcohol Intake• Even moderate amounts place fetus at risk of:

Lower IQ Attention Deficits Learning Deficits Reduced Social Competence

• First Trimester exposure: skull and facial abnormalities

• Later in pregnancy: postnatal growth affected

Radiation fetal brain most vulnerable to radiation exposure 8th

– 15th week of pregnancy Decrease in IQ scores Impaired school performance Susceptibility to seizures Changes in the occurrence of major features of

physical development

Maternal Age Malnutrition

◦ Effect in Last Trimester ◦ Nutritional demands of late fetus is greatest

Apgar developed by Dr. Virginia Apgar in 1953. It is administered

at 1 minute after birth and again at 5 minutes after birth.• A perfect score is 10 see table on page 126• A = Appearance color should be completely pink• P = Pulse heart rate should be adequate (over 100

beats per minute)• G = Grimace - reflex irritability vigorous cries or

withdrawal• A = Activity muscle tone should be strong, an active

motion• R = Respiration a good, strong cry

Brazelton Neonatal Behavioral Assessment Scale (NBAS-R)

developed by Dr. Berry Brazelton in 1973 and revised in 2000• A detailed look at the child’s physical and behavioral

functioning shortly after birth• Used to assess behavioral capabilities of newborns up to

20 days of age• Looks at 28 behaviors and 18 reflexes in these 7 areas:

Habituation Social Interaction MotorState Organization

Reflexes State RegulationAutonomic System

Sensory Capability - Receptors◦ vision◦ hearing◦ smelling◦ tasting◦ feeling

Sensation - firing of receptors by stimulus Perception - interpretation of sensory

input

Nativism - innate - nature Empiricism - experience - nurture Behavioral Systems Approach –

◦ Perception is due to both

Common to all methods - Change in Behavior correlated with change in Stimulus

Visual Preference (Fantz) Visual Cliff (E. Gibson & Walk) Habituation-Dishabituation Operant Conditioning Procedures

Looking Chamber Reflection of stimulus on cornea The “Basic Problem”

◦ Change in behavior - time gazing ◦ Change in stimulus - different visual stimuli

Limitations – There may be perception even though there is no

preference

Depth Perception “Deep” vs. “Shallow” end Mother entices the child to crawl Limitations

◦ Child or kid must be ambulatory◦ Overcome by monitoring heart rate of babies

suspended over each end (Campos)

Babies can’t suck & listen (watch) at same time.

Establish sucking response Disrupt it with repeated stimulus (e.g., “Pa”) With repetition of Pa, child habituates

◦ sucking returns A new stimulus (e.g., “Ba”) is introduced If child perceives difference between Ba & Pa,

sucking stops - Dishabituation

Behaviors which are reinforced become more frequent

Researcher reinforces response to one stimulus and not to another

If child perceives difference between stimuli than will respond more to reinforced stimulus

Perception◦ Responses: e.g., head turning, sucking, kicking◦ Reinforcers: e.g., mother’s voice, milk, visual

stimuli, heartbeat. Memory & Cognition

◦ Kicking mobile in presence of an X produces conjugate reinforcement

◦ In later testing immediate kicking when X is present shows recall of contingency (remembering)

Early Perception◦ Dr. Seuss passages read by mothers in last

trimester.◦ Infants suck to produce mother-read passages.

Early Socialization◦ Infant social referencing.

Some abilities are hard wired Examples

◦ Detect light from dark◦ Detect horizontal from vertical◦ Detect sound (phoneme) boundaries

Hard - Wired Present at birth Do not need much experience

◦ Unlearned thus “Unconditioned” Reflex is not a behavior but stimulus-

behavior relationship

Consummatory Defensive Social

1. Reflexes May Stay the Same 2. Reflexes May Disappear 3. Reflexes May Be Elicited by New Stimuli

- Respondent Conditioning 4. Reflexes May be Elaborated into New

Behaviors - Operant Conditioning