Prenatal development

PSYC 160: Life Span Development - Prenatal Development

1. Learning Objectives

  • Describe the course of prenatal development

  • Understand typical prenatal development

  • Describe hazards to prenatal development

  • Describe prenatal care

2. Course of Prenatal Development

2.1 Stages of Development

  • Germinal Period (First 2 weeks after conception)

    • Creation of the zygote

    • Continued cell division

    • Attachment to uterine wall

    • Blastocyst: Inner layer developing into embryo

    • Trophoblast: Outer layer providing nutrition and support

  • Embryonic Period (2-8 weeks after conception)

    • Mass of cells termed an embryo

    • Intense cell differentiation into three layers:

      • Endoderm: Inner layer

      • Mesoderm: Middle layer

      • Ectoderm: Outer layer

    • Development of life-support systems and organs

      • Amnion: Fluid-filled sac protecting the embryo

      • Umbilical Cord: Connects fetus to placenta (contains 2 arteries and 1 vein)

      • Placenta: Tissue group where maternal and fetal blood vessels intertwine

    • Organogenesis: Formation of organs occurs

  • Fetal Period (2 months to birth)

    • Lasting approximately 7 months

3. The Three Trimesters of Prenatal Development

3.1 First Trimester (Conception to 12 weeks)

  • 4 weeks: Less than 1/10 inch long

  • 8 weeks: About 0.6 inch long, beginnings of major systems

  • 12 weeks: About 2 inches long, rudimentary facial features, heart and limbs forming

3.2 Second Trimester (13-28 weeks)

  • 16 weeks: About 5 inches long, heartbeat detectable, movements start

  • 20 weeks: About 6.5 inches long, skin developing, hair beginning

  • 24 weeks: About 12 inches long, weight increasing, can respond to stimuli

3.3 Third Trimester (29-40 weeks)

  • 28 weeks: About 15 inches long, gaining weight

  • 32 weeks: About 17 inches long, bones softening

  • 36-38 weeks: About 19-20 inches long, body fat accumulation, may assume birth position

4. Teratology and Hazards to Prenatal Development

4.1 Teratogens

  • Teratogen: Any agent that causes birth defects or affects cognitive/behavioral development

  • Teratology: Study of birth defects' causes

  • Damage severity influenced by:

    • Dose of teratogen

    • Genetic susceptibility

    • Timing of exposure

  • Negative fetal effects: Stunted growth, brain development issues, organ functioning problems

4.2 Prescription and Nonprescription Drugs

  • Teratogenic Prescription Drugs: Antibiotics (streptomycin, tetracycline), some antidepressants

  • Nonprescription Drugs: Diet pills, high doses of aspirin

4.3 Psychoactive Drugs

  • Affect the nervous system and can lead to:

    • Caffeine: Potential risks

    • Methamphetamine, cocaine: Neurological and developmental deficits

    • Marijuana: Low birth weight, greater NICU likelihood

    • Heroin: Withdrawal and behavioral issues

4.4 Alcohol Consumption

  • Fetal Alcohol Spectrum Disorders (FASD): Learning and behavioral issues due to maternal alcohol consumption

  • Associated with higher risk of early death

4.5 Nicotine Exposure

  • Associated with low birth weight, ADHD risks, compromised brain development

4.6 Environmental and Maternal Factors

  • Incompatible Blood Types: Risks per prenatal development

  • Environmental Hazards: Radiation, toxic substances

  • Maternal Diseases: Rubella, syphilis, diabetes

  • Maternal Diet and Emotional State: Importance of nutrition, emotional health

5. Prenatal Care

  • Importance of screening and treatment for manageable conditions

  • Educational, social, nutritional services support

  • Exercise guidance during pregnancy

  • Integration of doulas for enhanced prenatal support and outcomes

  • Relationship to reduced preterm births, low birth weight, and NICU admissions