Prenatal Development

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Prenatal Development

• Lecture 4
• C6035 Human Development

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Course of Prenatal Development The Germinal
Period

• First two weeks after conception
• Zygote is created attaches to uterine wall
• Cell division begins
• Blastocyst inner layer of cells which later
  develop into embryo
• Trophoblast outer layer of cells that provide
  nutrition support for embryo
• Implantation attachment of zygote to uterine wall

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Course of Prenatal DevelopmentThe Embryonic
Period

• from two to eight weeks following conception
• cell differentiation intensifies
• support systems for the cells form
• organs appear
• Endoderm inner layer of cells which later form
  digestive respiratory systems
• Ectoderm outer layer of cells which becomes
  nervous system, sensory receptors skin parts

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Course of Prenatal DevelopmentThe Embryonic
Period

• Mesoderm middle layer of cells which becomes
  circulatory system, bones, muscles, excretory
  reproductive systems
• Placenta life-support system consisting of group
  of tissues in which small blood vessels from
  mother offspring intertwine
• Umbilical Cord life-support system, containing
  two arteries one vein, that connects baby to
  placenta.
• Amnion bag or envelope containing clear fluid
  where developing embryo floats

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Course of Prenatal DevelopmentThe Fetal Period

• From two months following conception to birth
• First Trimester from conception to 12 weeks
  features growth of arms, legs, brain face is
  where heartbeat is detectable
• Second Trimester between 12 to 24 weeks
  features development of skin, hair,
  finger/toenails where movement such as
  thumb-sucking hiccups are noticeable
• Third Trimester from 24 to 38 weeks where
  increased activity, periods of sleep assumption
  of birth position are noticed

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Miscarriage and Abortion

• Miscarriage is spontaneous abortion occurring
  before developing organism is mature enough to
  survive outside womb
• Deliberate abortion is by choice involves
  medical procedure
• Selective abortion is legal in United States
  that during first trimester, mother her doctor
  can make choice without consulting others
• Abortions occurring later than first trimester
  can have stipulations attached either
  legislatively or by courts

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Teratology and Hazards To Prenatal Development

• Teratogen agent that causes birth defect
• Maternal Factors emanating from mother are age,
  nutrition, emotional state and stress
• Toxoplasmosis disease caused from parasite
  ingested from eating raw meat, or touching cat
  feces
• Ectopic Pregnancy presence of developing embryo
  or fetus outside normal location in uterus

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Teratology and Hazards To Prenatal Development

• Fetal Alcohol Syndrome cluster of abnormalities
  that appears in offspring of mothers who drink
  alcohol heavily during pregnancy
• Paternal Factors emanating from father are
  exposure to lead, radiation, pesticides,
  petrochemicals
• Also, fathers who have a diet low in vitamin C,
  often produce offspring with higher risks of
  birth defects cancer

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Environmental Hazards

• Pollutants, toxic wastes, chemicals radiation
  can cause birth defects or adversely affect
  developing fetus
• Recent research has shown that prolonged exposure
  by mothers to heat in saunas or hot tubs also
  endanger fetus
• Fetal Surgery and Therapy is a recent practice in
  which surgical treatment is used to correct
  possible defects before permanent damage results
  after birth.

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Expectant Parents

• Confirming the Pregnancy/Calculating the Due Date
  length of pregnancy is calculated from first day
  of womans last menstrual period lasts an average
  of 280 days, or 40 weeks
• Preparation For Babys Birth fetus descends into
  pelvic cavity signaling beginning of birthing
  process
• End of the pregnancy is noticeable as babys
  head presses against mothers pelvis her cervix
  becomes softer thinner

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Expectant Mothers Nutrition, Weight Gain and
Exercise

• Nutrition and Weight Gain - Average weight gain
  is from 25 to 35 pounds, at a rate of
  approximately 4.4 pounds during first trimester
  followed by an average of 1 pound per week
  thereafter
• Recommended daily allowance for all nutrients
  increases during pregnancy
• Exercise during pregnancy helps prevent
  constipation, conditions the body, is
  associated with a more positive mental state

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Culture and Prenatal Care

• How pregnancy is viewed culturally often
  determines quality of prenatal care
• When viewed as a natural occurrence as opposed to
  medical condition, prenatal care is not priority
• Culture influences health care practices during
  pregnancy such as in Mexican-American families
  where mothers older women play essential role
  during prenatal period birthing process

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