Prenatal Development, Birth and The Newborn Behavioral Science Tues, Jan

Prenatal Development Overview 3 Stages Major achievements of each stage Prenatal Developments Basic Concepts Critical periods Teratogens

3 Stages of Prenatal Development Germinal Stage Embryonic Stage Fetal Stage

Germinal Stage Start – conception End – attachment to uterine wall Major achievements Rapid cell division Attachment to uterine wall

Embryo Stage 2 nd to 8 th week Start – attachment to uterine wall End – formation of bone cells Major achievements Growth (from ¼ inch to 1 inch) Major organs formed (~6.5 weeks) Movement

Critical Periods The developing child is most susceptible to teratogens during the embryonic stage This is when most of the major organ systems form and begin to function Each organ has a specific critical period And is influenced by different teratogens: E.g., Alcohol (FAS), Radiation, Tobacco, Maternal Disease

Fetal Stage 8 th week to ~38 weeks Start – formation of real bones End – birth Major achievements Growth (3 in. -> 20 in.) Movement felt by mother Hearing (~5months) Sensitive to light

Ovum The ovum is embedded in follicle cells

17 th century drawing of Human sperm By Hartsoeker The miniature human was thought to grow once it entered the ovum

Sperm in the presence of an ovum

Ovum Sperm

The Germinal Stage

Overview of Germinal Stage

The Embryonic Stage

The start of the embyronic stage Implantation in uterine wall

Neural Tube (26 days) Head Heart Starts beating ~18 days 3 mm 0.12 in.

Chorion – develops into placenta

Heart Head ~ 3.5 weeks

Eye Mouth Nostrils Face at ~4.5 weeks

Eye Arm Leg 6 weeks

5 – 6 Weeks 1.5 cm 0.6 in Primitive human form

Eye at 6 ½ weeks Eyes close ~ 9 weeks Open again at 7 months

7 th week

The Fetal Stage

Formation of bone cells Beginning of the Fetal Stage

Fetal Movement

Fetal thumb sucking

4 1/2 months 25 cm 10 in.

5 ½ months 30 cm 12 in Layer of fat protects the skin (vernix)

Hand 5 weeks - bud 3 months - fingers 17 weeks – fingernails

Fetus and placenta

5 months 25 cm 10 in.

7 months Growth slows – If same growth rate continued the child would weigh ~200 lbs at birth 16 inches / 3 lbs Viable – able to survive outside the womb Age of viability now between weeks Digestive / Respiratory systems working Babies born as little 1.5 lbs have been able to survive

Brain Development Occurs throughout prenatal period and after birth 3 major aspects Cell proliferation Development of new neurons Cell migration Neurons move to “proper” location Cell differentiation Neurons specialize

Birth Average Length = 20 inches Average weight = 7 lbs

Right after birth A few hours later

Effects of Alcohol Fetal Alcohol Syndrome High levels of prenatal exposure influence physical structure Lower levels of prenatal exposure influence neurochemistry Long lasting effects See Hunt et al., 1995

Low Birthweight

Cost of Low Birth Weight

The Newborn Assessment of Newborn Functioning Apgar Assessment Brazelton Neonatal Behavioral Assessment BNBAS Reflexes

APGAR Developed by Virginia Apgar (1950s) At birth – mother was the focus of attention Needed some sort of quick assessment of the infant Used right after birth Does not require much training

APGAR 5 Scales (all scored 0, 1, 2) Appearance Heart Rate Response to Stimulation Muscle Tone Respiration

APGAR Appearance (color of skin) 0 = gray / blue skin color Indicates lack of oxygen 1 = pink body / gray or blue hands Indicates lack of oxygen in extremities 2 = pink tone over entire body

APGAR Heart Rate 0 = no heart beat seen, heard, or felt 1 = less than 100 beats per minute 2 = 100 – 140 beats per minute Response to Stimulation Response to birth Response to suctioning of mouth / nose 0 = no response 1 = moderate of low response 2 = facial grimace / coughing / wheezing

APGAR Muscle Tone 0 = completely limp 1 = moderate muscle tone / limbs moderately flexed 2 = good muscle tone / limbs flexed & active Respiration 0 = no breathing within 60 seconds 1 = irregular or slow breathing 2 = good breathing / strong cry

APGAR Administered twice At 1 or 2 minutes and And again at 5 minutes Scores greater than 7 at 5 minutes indicate the infant is ok Likely no intervention is necessary Scores less than 4 indicate infant is in trouble Requires immediate attention

APGAR Scores on Apgar are strongly related to infant mortality Lower Apgar scores are related to a greater chance of the infant dying within the first year of life Mortality rates in US have dropped But rank far behind other countries US Ranked # 27 in world Recent data suggests US has dropped farther

Infant Mortality Rates (Deaths per 1000 live births)

Brazelton Neonatal Behavioral Assessment Scale (BNBAS) Developed by T. Berry Brazelton, 1973 Designed to assess infant functioning over the first month of life Covers a wide range of behaviors Often used as a research tool Requires extensive training Requires ~45 minutes to administer entire asessment Should administer twice – use the higher score – greater validity

BNBAS Covers a broad range of behaviors Neurological items Based on the intensity of response Mainly focuses on reflexes 0 = Absent -> 3 = Appropriate response Behavioral items Focus on state of arousal (sleep to crying) 9 point scale used –  for most item midpoint is optimal

REFLEXES Automatic, stereotyped response to a specific stimuli Recent research suggest reflexes are variable Not completely the same every time Variability may be important for learning Enables the infant to “explore” the environment Learn about contingencies

Sucking Reflex Present Prenatally Stimuli - Touch face near lips Response – Sucking motion Becomes a skill (under voluntary control) by 3 months

Babinski Reflex Elicited by stroking the foot Response – Depends on age Infants – 0 to 3 months Toes fan out Older individuals Toes curl in

Moro Reflex Elicited by sudden drop Response Hands and legs go out to side and then return to middle Present at birth Drops out at about 6 months

Stepping Reflex Elicited by holding infant upright and moving them across a surface Response Rhythmic walking behavior Present at birth Drops out at ~ 4 months

Warning Signs of Neurological Problems Absent Reflex Weak or Delayed Reflex Unequal or Asymmetric Bilateral Reflex Reflex that re-emerges after it has dropped out Reflex that is supposed to drop out but doesn’t