Prenatal Development

1
Prenatal Development

• Period from fertilization to birth.
• Subdivided into 3 periods Germinal, Embryonic
  and Fetal
• Germinal Period
• First 2 weeks
• Zygote (fertilized egg),
• cell division early differentiation into
  blastocyst (inner layer to become embryo) and
  trophoblast (outer layer to provide nutrition and
  structural support)
• attachment to uterine wall.

2
Prenatal Development ctd

• Embryonic period
• 2 to 8 weeks or after attachment to uterine wall
• Cell differentiation into systems and organs
• Endoderm (inner layer) will become digestive and
  respiratory systems
• Ectoderm (outermost layer) will become nervous
  system, sense organs, and skin
• Mesoderm (middle layer) will become circulatory
  system, bones, muscles, and reproductive.
• Placenta, umbilical cord and amnion develop from
  the fertilized egg to supply nutrients and
  protection to embryo.

3
Prenatal Development ctd.

• Fetal period (2 to 7 months)
• Activity, limbs, facial features, genitals
• Later, fingernails and eyes
• Later, fat and increased organ function
• Another way to divide the prenatal period is into
  3, 3-month Trimesters

4
Environmental Factors Affecting Prenatal
Development

• Teratogen environmental agent causing birth
  defect (environment means the placenta)
• Drugs
• Incompatible blood type
• Pollutants
• Infections (ie viruses)
• Nutritional deficiencies

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Teratogens - Drugs

• Prescriptions drugs
• Thalidomide a tranquilizer used in the early
  1960s to treat morning sickness.
• Antibiotics
• Antidepressants
• Hormones
• Accutane
• Over the Counter Drugs
• Diet pills, aspirin, caffeine

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Teratogens Drugs ctd.

• Non-Prescription Drugs
• Psychoactive modify mood or consciousness
• Alcohol FAS defects of face, limbs, and heart
  and a predisposition to alcohol use.
• Nicotine death, premature birth, low birth
  weight. Also cognitive, language, and
  respiratory problems.
• Cocaine reduced birth weight, body proportion,
  attention, sensory processing
• Marijuana tremor, startle response, verbal and
  memory deficiency
• Heroin and Methadone withdrawal, behavior and
  attention problems.

7
Teratogens - Environmental

• Radiation
• Carbon monoxide
• Mercury
• Lead
• PCBs
• Heat from hot tubs/saunas

8
Teratogens - Infections

• Rubella
• Syphilis
• Herpes
• AIDS
• Prenatally - Across placenta
• During birth By blood
• Post-partum Breast feeding

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Other Risks for Birth Defect

• Malnutrition
• Stress
• Maternal Age (lt 20, gt40)
• Paternal Factors
• Radiation, lead, pesticides, petrochemicals, low
  vitamin C, cocaine, marajuana, smoking, advanced
  age

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Correcting a Myth

• Pregnancy is not an illness.

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Some Terms

• Low birth weight (lt 5 1/2 pounds)
• Preterm (3 or more weeks early)
• Small for date (low in weight given the length of
  the term, which may be short or normal.

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Assessing Health at Birth

• Apgar Scale
• 1 to 5 minutes after birth.
• Heart rate, respiration, muscle tone, color,
  reflex rated 0, 1, or 2.
• Score of 7 to 10 is good health
• Score of 4, 5 or 6 may mean developmental
  problems
• Score of 3 or lower is an emergency

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Assessing Health at Birth ctd.

• Brazelton Scale
• 24 to 36 hours after birth
• 27 categories including neurology, 16 reflexes,
  and responses to people

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Postpartum Period

• Applies to the mother, not the infant
• About 6 weeks
• Until body has returned to pre-pregnancy
• Adjustment and adaptation of the mother and her
  body
• Includes bonding a close connection, especially
  physical, between caregiver and newborn.