Psychology 235 Child Psychology Dr. Blakemore Prenatal Development Psychology 235 Child Psychology Dr. Blakemore

Periods of Prenatal Development Period of the Ovum or Zygote, or Germinal Period - first two weeks Period of the embryo - 2 to 8 weeks Period of 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

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 From Berk, 3rd. Ed. P. 90

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

Seven - week embryo From Berk, 3rd. Edtion, p. 94

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 From Berk, 3rd ed., p. 98

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

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 Rubella HIV/AIDS Syphilis Blindness Deafness Mental Retardation

Prenatal Environment Zika In first, perhaps also second, trimester Associated with fetal microcephaly

Prenatal Environment Other influences radiation, emotional stress