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 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 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 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 doesnt