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"Physiology is NOT merely interested in getting the baby out of the uterus. 

Physiology at it's best wants mother and baby to meet in a specific neuroendocrine state.

Labor is a major neuromodulation."

- Ann Maria Rossetti, midwife, author, director of SEAO® and Sp®BAT

This article will set a foundation to create context and identify when your own body/mind shift between rest and digest and fight, flight or freeze states.

You will gain clarity of how the pregnant body has all the power within to grow baby and birth without fear.


The Parasympathetic Nervous System (PNS) is often referred to as rest and digest, homeostasis, or reserving energy.

The Sympathetic Nervous System (SNS) is often referred to as fight, flight, or freeze. Long term activation in pregnancy create hypertension in healthy pregnancies or pre-eclampsia in already high-risk pregnancies.

Our nervous system is more complex than thinking it operates like a light switch - ON or OFF. It receives triggers throughout the day signaling varied functions to operate relating to our whole being. 

But considering ON or OFF can help identify which state you are in. If in an SNS response: navigate a return to the PNS - as soon as possible - to aid in pregnancy, labor, and healing postpartum.

In pregnancy all placental hormones naturally trigger the Parasympathetic Nervous System.


Biological effects

  • Growth of uterus, tissues, glands, breasts
  • Augmentation of body fluids even amniotic fluid
  • Hemodilution / Hematocrit % drop
  • Myometrial sensitivity
  • Cerebral, uterine, vaginal receptors for oxytocin
  • Smoothing joins through production of relaxin
  • Fetal estriol and active fetal movements

Behavioral effects

  • Emotional openness - not keeping feelings in, open to sharing by talking and emoting 
  • REM phase/dreams - able to release stress of life through dreams/intuition
  • Regression baby brain - increasing sensitivity - mother’s brain is simple and focus to meet baby 1:1. Mother feels similar to newborn baby. She is re-born.
  • Empathy
  • Prosocial behavior - meeting and being with other moms


Biological effects

  • Placental growth and nourishment
  • Relaxation of smooth muscles (gut, stomach, uterus)
  • Creates the physical womb
  • Slow digestion = higher absorption of nourishment
  • Slows down neur-skeletal control - slow down thoughts and circadian rhythm - time doesn’t exist… wake up only do a couple things, then it’s 6pm - where did time go? Baby is included in thoughts and everything in life.)
  • Decreases blood pressure
  • Triggers Parasympathetic nervous system

Behavioral effects

  • Slow brain waves
  • Slow circadian rhythm
  • Altered perception of time
  • Psycho-emotional womb


Biological effects

  • Contraction of smooth muscles
  • Fetus and milk ejection
  • Raises body temperature
  • Actives immune system
  • Speeds wounds healing
  • Activates Parasympathetic nervous system

Oxytocin cannot work on target organs without PNS activation.

In obstructive labors, when cervix will not open, even though Pitocin is given:

  • Cervix (uterus) / nipple (mammary gland) will receive information from pitocin to contract, but will not open until the PNS fibers have communicated to the cervix sphincter to open up.

Behavioral effects

  • Empathy
  • Forgiveness
  • Anxiolytic - decreases stress
  • Altered state of consciousness
  • Self-esteem
  • Trust


Biological effects

  • Synthesized on the placental’s maternal side to reinforce its adherence
  • Natural pain killers
  • Empower immune system
  • Oxygenation in tissues
  • Activation of PNS

Behavior effects

  • Peace trance
  • Relaxation
  • learning processes
  • laughter / euphoria

Prolactin (new mother's best friend)

Biological effects

  • Growth of breast and uterus
  • Increases appetite and fat deposition
  • Alters glucose metabolism acting as insulin
  • Helps cope with stress

Behavior effects

  • Urge to take care
  • High resistance to sleep deprivation / less tired
  • Highest resistance to daily/ordinary routine / less exhausted
  • Reception of one’s own maternal competence / less questioning ability and capability
  • Maternal behavior

Cortisol on Fetal-Placental System

(in pregnancy / not applicable for birth)

"I cannot sleep at night." Waking up rhythm.

  • 60% of mother’s cortisol is deactivated by placental enzymes.

Cortisol helps synthesize prostaglandine:

  • Groups of lipids which help control inflammation, blood flow, and help induction of labor - when ready.
  • In labor prostaglandines dilate (widen) the cervix and cause uterine pulses.‚Äč

The fetus transforms cortisol into cortison.

Physiological stress in mothers make babies more strong and able to cope with stress in life.

This is where cultivating the ability to identify a peak in the Sympathetic Nervous System with the ability to return to a state of Parasympathetic Nervous System is necessary for healthy daily living.

The SNS is essential, but in typical daily life should be OFF more than ON.

Identify the ebb and flow

Like a teeter-totter the SNS and PNS will rise and fall throughout the day. 

When PNS is triggered often one will notice or feel:

  • Bonding
  • Trust
  • Low inflammation
  • Growth

When SNS is triggered too often one will notice of feel:

  • Fear
  • Separateness 
  • Anxiety
  • Low immunity

Labor pulsations / contractions

PNS Pulsations

Engage then pause. This is similar to how our gut works and blood flow works. This is how the uterus works. Good circulation in uterus. Stable vessel regulations. Vessels that pump.

Direction of engagement/contraction works with fiber of tissues mainly present on outside = down to up / stretching.

SNS Pulsations

Static contractions - no pause.  Like they never go away. Too tight small fibers. Less circulation to the fetal placental system.

If acute in labor one might observe obstructive labor and/or fetal heart rate distress.

Direction of engagement/contraction is like giving a squeeze, especially in the lower uterus; if stress is maintained, distress developes in contraction of fibers upper section of uterus. Fibers are more dense, causing the inability to stretch like in PNS response.

Intervention will likely be recommended.

The uterus is not an engine.

It responds best to a Parasympathetic Nervous System.

When a flower doesn’t bloom when it’s supposed to - you do not open the flower with your hands. You change the environment so it will bloom.

When cesarean section is necessary - restore the PNS as soon as possible. The intervention is a short time. Emergencies happen.

(Baby has their own birth, even when mom does everything "right." Birth-givers create life and energy that is separate from their own. The best of intentions may still require intervention.)

Mainstream culture STILL separates fetal well-being from mother. Like fetus/baby is an object to observe and not in relationship from the person who is living with the fetal placenta system.

If you are pregnant - center your physical and mental health today. Prioritize fulfilling relationships and friendships. Invest in your people and the life you desire to live. 

If you are supporting  - prioritize your focus with making mom most comfortable and confident in her decisions. Help her feel in control and liberated with the gift of creating child/ren and birthing a new generation.


Maternal stress and anxiety during pregnancy are linked to unfavorable neonatal outcomes with regard to both the physical and psychological development of the offspring, from the primal period to adolescence.
- Harvison, 2009

Sympathetic activation has been shown to be related to insulin resistance in out-of-pregnancy women, paving the way for possible interpretations and research on the increasingly high rate of gestational diabetes treated with diet or even with metformin and their relationship with chronic stress in pregnancy.
Kaaj RJ, Pöyhönen-Alho MK (2006)

Response (measured in brain waves) less clear than in the control group, between the potential evoked by the maternal voice and that of a foreign voice in 25 children of diabetic mother at one year of life.
Deregnier (2000)

An excess of sympathicotonia [SNS stimulation] at the uterine level can therefore cause a decrease in circulatory nutrition to the fetus with consequences such as IUGR in healthy pregnant women and preeclampsia in subjects with pre-existing hypertension.
Fisher (2004); Irestedt (1984); Shobel (1996)

Inspirational credit and gratitude to Di Anna Maria Rossetti for sharing this science in a digestible and applicable way for us birth-workers to spread far and wide.