Prenatal development stages, ect.

Definition of Prenatal Development Stages

The process of a baby growing and developing inside the mother’s womb, from conception (when the egg and sperm join) until birth.

Germinal Phase (Weeks 0–2), Where does it begin/end? Is it a zygote?

• Begins at fertilization → ends at implantation.
  

• The fertilized egg is a zygote.

Germinal Phase (Weeks 0–2), What day does implantation occur? Is it Germinal? How does it end?

• Implantation occurs ~day 14.
  

• “Germinal” = think germinate (like a seed sprouting).
  

• Ends when the zygote attaches to the uterus → becomes an embryo

Embryonic Phase (Weeks 3–8), What body structures appear? Does brain development start?

• Organ and body structure formation:

  • Arms, legs, torso, heart, brain begin developing.
    

Brain development starts very early (~week 3).

Embryonic Phase (Weeks 3–8), Does movement start? Why is it vulnerable? What does the brain appearance look like?

• Movement begins by the end of this stage.

• Vulnerability: most susceptible to toxins or damage.

• Most people don’t know they’re pregnant during this phase.
  

→ Brain Appearance:

• Early brain is smooth, later develops gyri and sulci (folds) to increase surface area.

More folds = more cortex = higher cognitive ability.

Fetal Phase (Week 9–Birth), is it the longest or shortest stage? What are the major developments?

• Longest stage of prenatal development.
  

• Major developments:

  • Growth, movement, and strength.

  • Hearing develops → fetus hears mother’s voice, heartbeat, and digestion.

  • Cognitive evidence: fetus remembers familiar rhythms (e.g., Cat in the Hat study)

Fetal Phase (Week 9–Birth), describe the attachment? What happens in a premature birth?

• Attachment:

  • Baby recognizes mother’s voice after birth.

  • But attachment can form with any caregiver — it’s not exclusive to biological parents.
    

• Premature birth:

  • Viability begins ~22 weeks (with medical support).

  • Female fetuses tend to survive prematurity better due to:
    

More developed lungs and immune system (testosterone redirects resources in males toward physical growth).

What’s the sequence of Early Brain Formation? What day?

• Neural Plate (≈ Day 18)

• Neural Groove (day 18–20)

• Neural Tube (≈ Day 24)

What’s the neural plate?

Flat rectangle on the embryo’s back.

What’s the Neural Groove?

Indentation forms in the plate.

What’s the Neural Tube?

 Groove closes into a tube.

Key factors in neurodevelopment (first 4), state definitions

• Neurogenesis

• Neuronal migration

• Synaptogenesis

• Myelination

• Neurogenesis (formation of new neurons)

• Neuronal migration (movement of neurons to their proper locations)

• Synaptogenesis (forming synapses/connections)

• Myelination (insulating axons to speed signaling

Key factors in neurodevelopment (last 3), state definitions

• Synaptic pruning

• Neurotransmitter system development

• Hormonal influences

• Synaptic pruning (removing weak or unused connections)

• Neurotransmitter system development (brain builds the chemical signaling systems)

• Hormonal influences (e.g., cortisol, thyroid hormone, sex hormones)