Notes on the Psychology of Childbirth

Special Topics in Biological and Cognitive Psychology

• Course Title: Psychology of Childbirth
• Instructor: Prof. Kalina Christoff Hadjiilieva

Learning Objectives

• Understand the differences between skeletal and smooth muscles.
• Explore sensory and motor innervation of the uterus in both pregnant and non-pregnant states.
• Distinguish the myometrium and the endometrium.
• Comprehend motor and sensory denervation in the term pregnant uterus.
• Identify differences in denervation of the myometrium and endometrium.
• Explain different stages of labour and their relationship to pain.
• Understand the placenta's functions and vascular complexity.
• Overall concept: Pregnancy as muscle gain.

Skeletal Muscles vs. Smooth Muscles

• Skeletal Muscles:
  • Attached to bones; responsible for voluntary movement.
• Smooth Muscles:
  • Found in internal organs; involuntary control.

Control of Muscles

• Direct control over muscles is facilitated by the Peripheral Nervous System (PNS):
  • CNS: Brain and spinal cord.
  • PNS: Cranial and spinal nerves, includes enteric neurons for the digestive tract.

Muscle Innervation Types

• Somatic Nervous System:

  • Involuntary movements (e.g., touch, hearing).

• Visceral Nervous System:

  • Control of visceral muscles and sensations.

• Efferent (Motor) Innervation:

  • Skeletal muscles via the somatic; smooth and cardiac muscles through the autonomic nervous system.

Uterine Anatomy

Non-Pregnant vs. Pregnant Uterus

• Nulliparous (non-pregnant) Uterus:
  • Weight: $44 ext{g}$
  • Volume: $10 ext{ml}$
  • Dimensions: Height $6-8 ext{cm}, Width 5 ext{cm}$
• At Term (Pregnant Uterus):
  • Weight: $1,100 ext{g}$
  • Volume: $5 ext{liters} ext{(5000 ml)}$
  • Dimensions: Height $40 ext{cm}, Width 22.5 ext{cm}$

Myometrium Changes

Smooth Muscle Fibers (Myocytes)

• Non-Pregnant Myometrium:
  • Length: $50 ext{µm}$
  • Width: $5 ext{µm}$
• At Term Myometrium:
  • Length: $500 ext{µm}$
  • Width: $15 ext{µm}$

Uterine Contractions

Non-Pregnant Uterus Contractions

• Frequency: All the time, spontaneously during menstruation or orgasm.
• Contraction Situations:
  • a) During menstruation
  • b) During orgasm
  • c) All the time
  • d) All of the above
  • e) None of the above

Pregnant Uterus Contractions

• Enters a state of uterine quiescence until late pregnancy (around 37-40 weeks).
• Develops spontaneous contractions and practice (Braxton-Hicks) contractions, along with contractions during orgasm and labor.

Uterine Denervation Changes

• At term (around 37-40 weeks), almost complete denervation of the uterus occurs, affecting both motor and sensory innervation profoundly.

Sensory and Motor Innervation

• The non-pregnant uterus receives sensory innervation for visceral sensations like distension/stretch, inflammation, and ischemia.
  • Sensory neurons enter through various levels of the spinal cord corresponding to their originating organ.

Summary

• Understanding uterine anatomy and its physiological changes throughout pregnancy is crucial for grasping the complexities of childbirth psychology and the biological interactions at play during this time.