Chapter 4: Zygote to Newborn

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Chapter 4 Zygote to Newborn

• Dr. M. Davis-Brantley

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Germinal Period The First 14 days

• Referred to as the first 2 weeks of development
  after conception
• OvumgtEgg travels the Fallopian tubegtSperm
  fertilizes egggtfertilized egg is later implanted
  in the uterus
• During these first days while the fertilized egg
  travels the fallopian tube there is rapid
  duplication and multiplication
• By the eight-celled stage, differentiation occurs
• Meaning early stem cells take on distinct
  characteristics and gravitate toward particular
  locations (the areas they will later become)
• The outer cells are to become the placenta their
  task is to achieve implantation
• 60 (natural conceptions) 70 (in vitro
  conceptions) fail to implant
• VideoThe 1st Month
• First 14 Days

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Embryo 3rd week through 8th week

• Video about the Embryonic Period
• VideoThe Embryo Takes Shape
• Characterized by the cells becoming a distinct
  being
• 4th week (1/8 inch)
• head, ears, eyes, nose, mouth
• blood vessel which will become the heart
• Cardiovascular system begins to show activity
• 5th week Embryo has grown twice in size
• Buds that will become arms and legs appear and
  tail-like appendage extends to form a spine

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Fetus 9th week until Birth

• 3rd month sex organs begin to take shape
• End of 3rd month
• the fetus has all its body parts
• Weighs 3 oz., and is 3 inches
• Video--Fetal Stage
• VideoFeeding the Growing Fetus

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Fetus 9th week until Birth

• 2nd Trimester
• Heartbeat becomes stronger
• Digestive system develops
• Excretory system develops
• Fingernails, toenails, and buds for teeth form
• Hair grows
• Brain significant growth (grown 6 times in size)
• Undergoing significant neurogenesis (develop new
  neurons)
• Undergoing significant synaptogenesis
  (connections b/n neurons)
• Age of Viability
• The age (22 weeks) at which the fetus can survive
  outside of the mothers uterus with specialized
  care
• Based on fetal brain functioning since the brain
  regulates the basic body functions

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Fetus 9th week until Birth

• 3rd trimester
• Odds of survival outside of the womb increase
  significantly each day
• There is maturation of the respiratory and
  cardiovascular systems
• Lungs begin to expand and contract
• Body weight increases rapidly to ensure that the
  developing brain is well nourished
• This decreases defects and difficulties in
  learning in the future
• Video3rd Trimester

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Risk Reduction

• Teratogens are agents and conditions that can
  impair prenatal development and lead to birth
  defects or even death
• Teratogens can include viruses, drugs, chemicals,
  stressors, and malnutrition
• Behavioral Teratogens are teratogens that can
  harm the prenatal brain which results in the
  child having difficulty with learning,
  hyperactivity, and antisocial behavior

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Risk Reduction

• Some teratogens cause damage only during specific
  prenatal periods
• Critical Period refers to the time when a
  particular organ or body part is most susceptible
  to teratogenic damage
• This is why obstetricians recommend couples get
  counseling, take multivitamins, stop taking
  medications before pregnancy

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Risk Reduction

• Threshold effectSome teratogens are virtually
  harmless until exposure reaches a certain level
• Ex Prenatal vitamins in excess can cause fetal
  abnormalities
• Interaction effectCondition whereby the risk of
  a teratogen causing harm increases when one
  substance intensifies the effects of another
  teratogen
• Ex Alcohol, tobacco, and marijuana

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Risk Reduction

• Genes can determine whether a specific teratogen
  will be harmful
• Ex degree of FAS, birth disorders such as cleft
  lip, cleft palate, and clubbing
• Ex Genes are implicated in the teratogenic
  effect that results in spina bifida

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Specific/Preventable Teratogens

• HIV as a teratogen
• Mothers transmit the virus during pregnancy and
  through breast feeding
• Can prevent transmission by
• Taking antiretroviral drugs beginning 14 weeks
• Give birth by cesarean section
• Does not breast feed
• Fetal Alcohol Syndrome (FAS)
• A cluster of birth defects caused by mother
  consuming alcohol during pregnancy
• Defects include abnormal facial features, slowed
  physical growth, slowed mental development
• Damage increases when alcohol is combined with
  other psychoactive drugs (cigs, cocaine, meth,
  LSD, psychotropic medications, etc)

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Small Babies

• Low birth babies
• A birthweight of less than 5 ½ pounds
• Due to the fetus growing too slowly
• Preterm birth
• Birth that occurs 3 or more weeks before full
  term, that is 35 or less weeks
• Small for gestational age
• Birthweight significantly lower than expected
• Typically a sign of serious problems
• Psychoactive substance use, malnutrition

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The Birth Process

• During the final month, fetus typically changes
  position to prepare for birth proces
• Short VIDEO and Extended VIDEO
• Babies that are breech are positioned so that
  buttocks, feet, or knees first (1 in 20 babies
  are breech)
• At 266th day after conception, the fetal brain
  sends a message to release certain hormones that
  pass through the mothers bloodstream
• This hormone triggers uterine muscles to contract
  and relax, which begins active labor
• Babies are born, on average, after 8 hours of
  active labor and 3 hours for subsequent births

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Newborns First Minutes

• Babies typically begin to breathe on their own
  and take first breaths with spontaneous cries
• Oxygen is entering for the first time and changes
  the babies skin color because of circulation
• Eyes open wide, Finger began to grab, toes
  stretch and retract
• Those attending to the child must remove mucus
  from the throat, umbilical cord must be cut to
  detach the placenta, baby is wrapped to preserve
  body heat

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Newborns First Minutes

• Apgar Scale is a means of quickly assessing a
  newborns body functioning
• The following is checked at birth and again 5
  minutes after birth
• Babys color
• Heart rate
• Reflexes
• Muscle tone
• Respiratory Effort
• A total score of 7 or higher indicates no danger

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Variations in Births

• Cesarean section is a surgical childbirth where
  there is an incision through the mothers abdomen
  and uterus to allow the fetus to be removed
  quickly
• Fewest Cesarean Sections occur in Ghana, Kenya
• Most take place in Mexico and Brazil

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Birth Complications

• Cerebral Palsy
• A disorder that results from damage to the
  brains motor centers. People with cerebral palsy
  have difficulty with muscle control, which can
  affect speech or other body movements
• Believed to be caused by excessive pain
  medication, slow breech birth, forceps but now
  discovered it often results from genetic
  vulnerability and maybe worsened by teratogens
• Anoxia
• A temporary lack of oxygen that can cause brain
  damage or death

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After Birth and Bonding

• Parental Alliance
• Cooperation b/n the mother and father because of
  their mutual commitment to their children.
• In a parental alliance, both parents agree to
  support each other in their shared parental roles
• Postpartum Depression
• A mothers feelings of sadness, inadequacy, and
  hopelessness in the days/weeks after giving birth
• Feelings are partly due to physiological
  (especially hormonal) and partly cultural,
  especially if the woman does not receive adequate
  assistance and encouragement from the father and
  helpers
• Parent-Infant Bond
• A strong loving connection that forms as parents
  hold, examine, and feed their newborn