Download Prenatal Development Germinal Period

Prenatal Development
Psychology 235
Child Psychology
Dr. Blakemore
Periods of Prenatal
Development
 Period
of
Germinal
 Period of
weeks
 Period of
the Ovum or Zygote, or
Period - first two weeks
the embryo - 2 to 8
the fetus - 2 to 9 months
Germinal Period- 0 to 2
weeks
Begins with fertilization at about day 14
of a woman’s menstrual cycle
 Fertilization takes place in the fallopian
tube - producing a zygote
 The first cell division takes place within
24 hours
 The cell continues to divide. When it
reaches the uterus it contains several
cells

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Implantation
Once in the uterus, the fertilized egg is
several cells in size -- called a blastocyst
 The blastocyst has an inner clump of
cells (will become embryo) and an outer
layer of cells (will become placenta,
membranes, etc.)
 The fertilized egg implants in the
uterine wall at about 10-14 days

Germinal Period
Period of the embryo
2 to 8 weeks
Begins as a clump of cells about the
size of the head of a pin
 Ends 6 weeks later fully formed about
one inch long
 Most important process is differentiation
 Very vulnerable time for damage

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Seven - week embryo
Period of the Fetus - 2 to 9
months
Growth - increase in size
 Beginning of function of organ systems
 28 weeks - viability - if born > 50%
survive
 At birth, 20 inches long, 7 pounds

Overview of Prenatal
Development
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Prenatal Environment

The baby develops in an environment,
which impacts development
Prenatal Environment
Maternal Age
 20 - 35 is ideal

Parity
 Higher parity, more degradation of
prenatal environment, but also
impacted by spacing

Prenatal Environment
Maternal diet
 an important consideration is protein
 folic acid is also important

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Prenatal Environment
Drugs
Can cross placental barrier
 most critical during embryonic period
 can be teratogens
 examples: thalidomide, DES, nicotine,
cocaine
 Alcohol leads to fetal alcohol syndrome,
or fetal alcohol spectrum disorder


Prenatal Environment

Maternal disease
– HIV/AIDS
– Syphilis

Rubella
– Blindness
– Deafness
– Mental Retardation
Prenatal Environment

Zika
– In first, perhaps also second, trimester
– Associated with fetal microcephaly
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Prenatal Environment


Other influences
radiation, emotional stress
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