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Prenatal Development Birth and the Newborn Baby

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					                       Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   1


       prenatal development, birth, and the newborn baby

Conception:
   Most conceptions happen from intercourse during a 3 day
    period: on the day of ovulation or in the 2 days prior.


Prenatal development:

 the period of the zygote (2 weeks)
   Implantation: zygote gets attached to the wall of the uterus (7th
     to 9th day)
        o blastocyst within 4 days of conception
                inner layer is embryonic disk.
                outer layer will develop into the amnion
        o Only about 70% of zygotes get successfully implanted.
        o By the end of the 2nd week, the chorion surrounds the
            amnion
        o Villi form the chorion burrow into the uterine wall, creating
            the start of the placenta.
        o placenta will permit food and oxygen to reach the
            developing organism and waste products to be carried
            away.
        o umbilical cord contains one vein that delivers blood with
            nutrients, and two arteries that remove waste products.

 period of the embryo: (2nd week to 8th week)
   embryonic disk forms 3 layers of cells:
          1) ectoderm (nervous system, and skin)
          2) mesoderm (muscles, skeleton, circulatory system,
             internal organs)
          3) endoderm (digestive system, lungs, urinary tract,
             glands)
   The second month: eyes, ears, nose, jaw, and neck form.
       o buds become arms, legs, fingers, toes.
       o heart develops separate chambers
       o liver and spleen start to produce blood cells.
       o about 1 inch long, it responds to touch, can move
                       Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   2


 Period of the fetus: (9th week to birth)
   3rd month: fetus can kick, bend its arms, form a fist, curl its toes,
    open its mouth, suck its thumb
        o the lungs start to expand and contract in rehearsal of
          breathing
        o by the 12th week, the external genitals are formed
        o heartbeat can be heard through a stethoscope
        o at the end of the 3rd month, the 1st trimester is complete

    2nd trimester:
        o vernix covers the skin, lanugo covers the body
        o at the end of this trimester, most brain neurons are in
            place
        o stimulated by sound and light

    3rd trimester:
         o age of viability: some time between 22 and 26 weeks
         o the cerebral cortex enlarges, fetus spends more time
            awake
         o around 24 weeks fetuses can feel pain
         o by 25 weeks, react to sounds with body movements
         o in the last week of pregnancy they learn to prefer their
            mother’s voices
         o gains more than 5 lbs and grows 7 inches in this trimester
         o in 8th month, a layer of fat is laid down
         o gets antibodies from mom

Prenatal Environmental Influences
 teratogens:
   effects on a structure worst when that structure is being formed
   not all embryos or fetuses are equally affected
   the same defect can be caused by different teratogens
   a single teratogen can result in several different kinds of defects
   longer exposure/higher dose increased likelihood of serious
     harm
   most of the organs and body parts develop in the period of the
     embryo
                     Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   3


Harm depends on several factors:
  1) dose
  2) heredity
  3) other negative influences
  4) age

   prescription and non-prescription drugs
       o thalidomide
       o DES (diethylstilbestrol)
             DES daughters are more likely to miscarry or
               delivery too early.
             DES sons may display a greater vulnerability to
               fertility problems and immune problems.
       o Aspirin
       o Caffeine
       o Cocaine, heroin, methadone
       o marijuana
       o tobacco
       o Alcohol: fetal alcohol syndrome, fetal alcohol effects
             no amount of alcohol during pregnancy is safe.

   Radiation
   environmental pollution
   infectious disease:
       o rubella
       o HIV
       o herpes viruses (cytomegalovirus, herpes simplex 2)
       o toxoplasmosis
                      Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   4


Other maternal factors
   exercise
   nutrition (e.g. folic acid)
   emotional stress
   Rh blood incompatibility
   maternal age and previous births

Childbirth

3 stages of childbirth:
 1st stage  dilation and effacement of the cervix
 2nd stage  birth of the baby
 3rd stage  delivery of the placenta or afterbirth


Baby’s adaptation to labor and delivery:
   force of contractions makes babies produce stress hormones:
        o help withstand oxygen deprivation by sending more
          blood to heart and brain
        o causes lungs to absorb excess liquid
        o makes the baby alert, ready to greet the world!
   average baby is 20 inches long and 7 ½ pounds at birth



Assessing the newborn’s physical condition

Apgar test
   heart rate (absent = 0; slow = 1; over 100 beats per minute = 2)
   respiration (absent = 0; slow = 1; good, crying= 2)
   muscle tone (0= limp; 1= weak, some flexion; 2= strong, active)
   colour (0=blue; 1= pink body, blue extremities; 2= pink)
   reflexes (0=no response; 1= frown/grimace/weak cry; 2=
     vigorous cry/cough/sneeze)
   score of 7 or higher at the 5 minute test are considered in ok
     condition
   4 or lower means trouble
                      Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   5


  Approaches to childbirth

   natural childbirth (a.k.a. prepared childbirth)
      o Classes
      o Relaxation and breathing techniques
      o Labor coach

 home delivery
   for healthy women who are assisted by a doctor or midwife, this
    is as safe as a hospital birth
   but if attendants aren’t well trained in the event of an
    emergency, the rate of infant death is high

Medical interventions
   fetal monitoring
        o Abnormal heartbeat can mean the baby is in distress

   labor and delivery medication
       o analgesics
       o anesthetics
             weakens uterine contractions during the 1st stage of
               labor and interferes with the mother’s ability to feel
               contractions and push during the 2nd stage
             results in prolonged labor
             newborn will be sleepy and withdrawn, suck poorly
               during feedings, and be irritable when awake

   cesarian delivery
      o 30 years ago 3% of births; now 21%-highest rate in world!
      o more time for recovery
      o baby may be sleepy, withdrawn, irritable
                      Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   6


Preterm and low-birth-weight babies
   Preterm: born several weeks earlier than their due date. Weight
     may be appropriate for time they spent in the womb

   Small for date: below their expected weight.
      o the most serious problems
      o death in 1st year; infections; brain damage
      o lower intelligence test scores, less attentive
      o inadequate nutrition before birth

   Preterm babies as a group are more at risk for child abuse.
   Isolette: controls temperature, sources of infection.
   respiratory distress syndrome: > 6 weeks early  serious
    breathing difficulties
   stimulation: rocking, heart beat, mom’s voice, soft music,
    promote weight gain, predictable sleep patterns, alertness
   massage
   parental training

Birth Complications
    Emmy Werner’s (1955) longitudinal study of infants with mild,
      moderate, or severe birth complications.
        o best predictor of how well they did in later years was the
          quality of their home environments.


The Newborn’s capacities

Reflexes:
 eye blink
 rooting
 sucking
 swimming
 Moro
 palmar grasp:
 stepping
 Babinski
                       Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   7


Newborn states:
    1) regular sleep, 8-9 hours a day
    2) irregular sleep, 8-9 hours a day. Includes REM sleep
    3) drowsiness; varies from kid to kid
    4) quiet alertness: 2-3 hors a day
    5) waking activity and crying; 1-4 hours a day

   sleep:
       o REM sleep: 50% of newborns’ sleep time!
       o special need for cortical stimulation provided by REM.

   crying:
       o physical needs: hunger, temperature, noise, pain.
       o provokes feelings of arousal and discomfort in adults

Sensory capacities:
   touch: sensitivity to touch is well developed at birth, especially
    around the mouth, palms, and soles of feet
       o temperature change
       o very sensitive to pain

   taste and smell: prefer sweet to salty. Expressions reveal
    preferences.
       o breast milk is ideally suited to support the infant’s early
          growth.
       o Babies like the smell of bananas, chocolate; do not like
          rotten eggs
       o preference for the smell of their mother’s amniotic fluid
       o preference for the smell of their own mother’s breast
       o preference for the smell of a lactating woman to formula

   hearing: newborns prefer voices and noises to pure tones.
    They can tell the difference between sound patterns (ma, ba)
      o prefer high-pitched voice, expressive, ends w. rising tone

   vision: least developed of the senses at birth.
       o Poor visual acuity (20/600); tracking is slow, inaccurate
       o Prefer colour rather than grey stimuli, but aren’t yet good
         at discriminating among colours
                     Lifespan overheads, chapter 3: prenatal development, birth, and the newborn   8



Neonatal Behavioural Assessment:

The Brazelton Neonatal Behavioural Assessment Scale (NBAS)
   some research findings:
        o Asian and Native-American babies are less irritable than
           Caucasian babies
        o NBAS recovery curves predict intelligence with moderate
           success well into the preschool years

				
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