Prenatal and Infant Development

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Prenatal and Infant Development

• Mr. Koch
• AP Psychology
• Forest Lake High School

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Conception

• A single sperm fertilizes a single ovum (egg) to
  create a zygote
• germinal stage - process of rapid cell division
  and then differentiation
• At about 10 days, attaches to wall of uterus
• Outer cells form placenta, inner cells develop
  into embryo

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Embryonic Stage

• Stage from 2-9 wks after conception
• Organs begin to form and function
• Develops heart, nervous system, stomach,
  esophagus, ovaries or testes
• Develop eyes, ears, nose, jaw, mouth lips
• By end have tiny arms w/ elbows, hands, fingers
• Legs have knees, ankles, toes

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Fetal Stage

• 7 month period of prenatal development, spanning
  9 weeks from conception to birth
• Begins to look distinctly human
• Organs grow and start to function
• By 3 months can kick, make fist, turn head, open
  mouth, swallow, frown
• In 6th month eyelids open, has tastebuds,
  well-developed grasp, can breathe regularly as
  long as 24 hrs. at a time
• Could potentially survive premature birth by end
  of 6th month
• Organ systems typically functional by end of 7th
  month
• 8th 9th month respond to light touch, hear
  outside sounds
• Can also learn respond differently to sound of
  mother (faster heartbeat) and stranger (slower
  heartbeat)

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Teratogens

• Potentially harmful agents (i.e. viruses,
  chemicals) that can affect prenatal development
• Placenta screens out most harmful substances, but
  these sneak through
• Especially harmful if during embryonic stage
• critical period in prenatal development
• If heart, eyes, ears, hands, feet dont appear,
  cannot form later if formed incorrectly,
  defects are permanent
• Teratogens during fetal stage affect size,
  behavior, intelligence, and health

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Teratogens

• Disease
• Can be born with AIDS or experience physical
  defects from other diseases like rubella
• Drugs (i.e. heroine, cocaine, crack)
• Can be born addicted
• Crack babies
• premature, underweight, tense, fussy, delayed
  physical growth motor development, behavior
  learning problems
• Smoking/nicotine
• Can cause respiratory problems, irritability,
  social/attention problems, greater risk for
  nicotine addiction later in life, can harm brain
  development
• Can cause reduction of nutrients that can lead to
  premature and underweight birth, which can cause
  cognitive and behavioral problems

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Teratogens

• Alcohol
• Can kill fetal brain cells depresses fetal
  nervous system, putting at risk for birth defects
  mental retardation
• Fetal Alcohol Syndrome (FAS)
• Characterized by mental retardation, possible
  physical malformations
• Behavioral and psychological problems also linked
  to mothers experiencing significant stress,
  depression, or flu in first 6 months
• Fortunately, vast majority of infants (gt90 in
  western nations) are born without mental or
  physical problems

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Newborns

• How do we study capabilities of infants?
• Very difficult present stimuli monitor
  response
• Eye movements, changes in heart rates, sucking
  rates, brain waves, body movements, and skin
  conductance
• Can see at birth
• Blurry, but able to see large, close objects
• Seem to prefer faces and seem prepared to
  distinguish from other visual stimuli
• Born with limited hearing capabilities
• Notice single note differences of tone, turn head
  toward sounds, particularly attuned to sounds of
  speech
• Similar sense of smell taste to adults, but
  less developed
• Breast-fed infants show preference for smell of
  own mother to others
• In general, infants sensory abilities seem to
  dispose to focus attention on caregiver

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Newborns

• Born with numerous reflexes that aid survival
• Involuntary, unlearned motor behaviors
• Ex. rooting reflex, sucking, etc.
• Most disappear in 3-4 months when brain
  development allows voluntary control of muscles
  and development of motor skills

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Newborns

• Brain development
• Born with overabundance of neurons, but immature
  (connections poorly developed)
• After birth, neural networks develop rapidly
  until puberty when pruning process gains
  importance

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Newborns

• Brain development helps enable maturation
• Natural growth or change that unfolds in a fixed
  sequence, relatively independent of environment
• Must be biologically prepared for certain changes
  to develop
• Age of maturation will vary, but sequence rarely
  does
• However, research shows that once properly
  matured, experience can impact efficiency,
  effectiveness of development
• Once again, nature and nurture interact