Prenatal Development Birth and The Newborn Behavioral Science
Prenatal Development, Birth and The Newborn Behavioral Science Tues, Jan 26 2006
Prenatal Development n Overview n 3 Stages n Major achievements of each stage n Prenatal Developments n Basic Concepts n n Critical periods Teratogens
3 Stages of Prenatal Development n Germinal Stage n Embryonic Stage n Fetal Stage
Germinal Stage Start – conception n End – attachment to uterine wall n n Major achievements Rapid cell division Attachment to uterine wall
Embryo Stage 2 nd to 8 th week n Start – attachment to uterine wall n End – formation of bone cells n Major achievements n n Growth (from ¼ inch to 1 inch) Major organs formed (~6. 5 weeks) Movement
Critical Periods n The developing child is most susceptible to teratogens during the embryonic stage n This is when most of the major organ systems form and begin to function n Each organ has a specific critical period n n And is influenced by different teratogens: E. g. , Alcohol (FAS), Radiation, Tobacco, Maternal Disease
Fetal Stage n 8 th week to ~38 weeks n Start – formation of real bones End – birth Major achievements n n n Growth (3 in. -> 20 in. ) Movement felt by mother Hearing (~5 months) 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
Implantation in uterine wall The start of the embyronic stage
Neural Tube (26 days) Head 3 mm 0. 12 in. Heart Starts beating ~18 days
Chorion – develops into placenta
~ 3. 5 weeks Head Heart
Face at ~4. 5 weeks Eye Nostrils Mouth
6 weeks Eye Arm Leg
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
Beginning of the Fetal Stage Formation of bone cells
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 n Growth slows – n If same growth rate continued the child would weigh ~200 lbs at birth n 16 inches / 3 lbs n Viable – able to survive outside the womb Age of viability now between 22 -26 weeks n n n Digestive / Respiratory systems working Babies born as little 1. 5 lbs have been able to survive
Brain Development n n Occurs throughout prenatal period and after birth 3 major aspects n Cell proliferation n n Cell migration n n Development of new neurons Neurons move to “proper” location Cell differentiation n Neurons specialize
Birth Average Length = 20 inches Average weight = 7 lbs
Right after birth A few hours later
Effects of Alcohol n Fetal Alcohol Syndrome n High levels of prenatal exposure influence physical structure Lower levels of prenatal exposure influence neurochemistry Long lasting effects n n n See Hunt et al. , 1995
Low Birthweight
Cost of Low Birth Weight
The Newborn n Assessment of Newborn Functioning n Apgar Assessment n Brazelton Neonatal Behavioral Assessment n n BNBAS Reflexes
APGAR n Developed by Virginia Apgar (1950 s) n At birth – mother was the focus of attention n Needed some sort of quick assessment of the infant n n Used right after birth Does not require much training
APGAR n 5 Scales (all scored 0, 1, 2) n n n Appearance Heart Rate Response to Stimulation Muscle Tone Respiration
APGAR n Appearance (color of skin) n 0 = gray / blue skin color n n 1 = pink body / gray or blue hands n n Indicates lack of oxygen in extremities 2 = pink tone over entire body
APGAR n Heart Rate n n 0 = no heart beat seen, heard, or felt 1 = less than 100 beats per minute 2 = 100 – 140 beats per minute Response to Stimulation n n Response to birth Response to suctioning of mouth / nose 0 = no response 1 = moderate of low response 2 = facial grimace / coughing / wheezing
APGAR n Muscle Tone n n 0 = completely limp 1 = moderate muscle tone / limbs moderately flexed 2 = good muscle tone / limbs flexed & active Respiration n 0 = no breathing within 60 seconds 1 = irregular or slow breathing 2 = good breathing / strong cry
APGAR n Administered twice n n n Scores greater than 7 at 5 minutes indicate the infant is ok n n At 1 or 2 minutes and And again at 5 minutes Likely no intervention is necessary Scores less than 4 indicate infant is in trouble n Requires immediate attention
APGAR n Scores on Apgar are strongly related to infant mortality n n 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 n But rank far behind other countries n n 1997 - 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) n Developed by T. Berry Brazelton, 1973 n Designed to assess infant functioning over the first month of life n Covers a wide range of behaviors n Often used as a research tool Requires extensive training Requires ~45 minutes to administer entire asessment Should administer twice – n n use the higher score – greater validity
BNBAS n Covers a broad range of behaviors n Neurological items n n Based on the intensity of response Mainly focuses on reflexes 0 = Absent -> 3 = Appropriate response Behavioral items n n 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 n Not completely the same every time n Variability may be important for learning n n Enables the infant to “explore” the environment Learn about contingencies
Sucking Reflex n Present Prenatally n Stimuli - Touch face near lips n Response – Sucking motion n Becomes a skill (under voluntary control) by 3 months
Babinski Reflex n Elicited by stroking the foot n Response – Depends on age n Infants – 0 to 3 months n n Toes fan out Older individuals n Toes curl in
Moro Reflex n Elicited by sudden drop n Response n n n 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 n Response n n Rhythmic walking behavior Present at birth n Drops out at ~ 4 months n
Warning Signs of Neurological Problems Absent Reflex n Weak or Delayed Reflex n Unequal or Asymmetric Bilateral Reflex n Reflex that re-emerges after it has dropped out n Reflex that is supposed to drop out but doesn’t n
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