Physiological birth 101 - what really happens.
If you're pregnant and have stumbled across this blog because you've seen the words "physiological birth" everywhere and are trying in vain to remember your Year 8 biology lesson on childbirth, you're in the right place. It's pretty wild that women have been giving birth for millennia, yet we're actually taught very little about how it actually happens.
This guide will help you understand the fascinating (and it's honestly fascinating) process of physiological birth and the science behind your body's natural design.
What is physiological birth?
Physiological birth is defined as a healthy, normal birth that occurs without medical intervention. It's the process that unfolds when labour and birth progress naturally, guided by the complex interplay of hormones and instincts that have evolved over thousands of years.
This doesn't mean it's the "right" or "only" way to give birth – every birth story is unique, and there are absolutely circumstances that require medical support to ensure the safety of you and your baby.
Understanding physiological birth helps us appreciate the remarkable capabilities of the human body and the conditions that support this natural process.
The history of birth. It's changed a lot!
Birth hasn't always looked the way it does in modern hospitals. Throughout history, birth was primarily a community-based experience, with women giving birth in their homes with support from other women who passed traditional knowledge down through generations.
If you want to hear more about the herstory of women and childbirth, I highly recommend listening to the first chapter of Dr Rachel Reed's book, Reclaiming Birth as a Rite of Passage. It will blow your mind.
The shift from home to hospital birth (starting in the 1930s) brought significant improvements in safety for situations requiring medical intervention. However, this transition also resulted in many practices developing in hospital settings without research to support them – simply because they felt culturally appropriate at the time.
Interestingly, we're now in a position where we need research to prove it's safe to stop certain practices that were implemented without evidence in the first place.
The Rite of Passage framework
Birth can be understood as a profound rite of passage. It's the transition of a woman into motherhood. Like other traditional rites of passage, it has three distinct phases:
Separation (Late pregnancy and early labour) Women begin to separate from their usual routines and focus inward as their body prepares for birth.
Liminality (Established labour) This is the "between" state where women often behave differently from their usual selves. The outside world fades away as they enter a deeply instinctual space.
Incorporation (Postnatal) The transition back to the world, but now transformed – meeting their baby and beginning the journey of motherhood.
Understanding birth as a rite of passage helps explain why the environment and support during this time can be so crucial.
Photo by Olivia Anne Snyder on Unsplash
The physiology behind the birth process
Your hormonal orchestra
Physiological birth relies on a complex interplay of hormones that work together beautifully:
Oxytocin: Often called the love hormone, this remarkable hormone serves multiple purposes. It creates the contractions that help your baby be born, but it also floods your system during skin-to-skin contact and breastfeeding, creating powerful feelings of love and connection. Oxytocin levels peak during birth and remain high in the immediate postpartum period, priming you for bonding with your baby.
Endorphins: Your body's natural morphine, endorphins provide pain relief during labour and create feelings of euphoria after birth. When the intense sensations of labour subside and endorphins remain high, many women experience a natural "birth high" that enhances the bonding experience.
Adrenaline: Provides bursts of energy when needed, particularly during transition, and ensures you're alert and protective of your newborn
Prolactin: Known as the mothering hormone, prolactin works alongside oxytocin to enable bonding behaviours. It's the hormone responsible for milk production, but it also creates those tender, protective feelings toward your baby. High prolactin levels help you feel calm and nurturing.
Early labour: The preparation phase
During early labour, your body is busy preparing for the birth of your baby:
Joints soften throughout your body
Your cervix begins to ripen and soften
Your baby's brain and lungs undergo crucial final developments
Oxytocin receptors form in your uterus
Research suggests that babies initiate labour once their lungs have matured, sending signals to their mother that they're ready to be born. Our babies are clever aren’t they?!
Established labour: The primal brain takes over
As labour becomes established:
Contractions become stronger, longer, and closer together, working in harmony to push your baby down into the pelvis.
Endorphins increase, creating an internal focus.
The thinking part of your brain (neocortex) reduces its activity.
Your limbic system – the primal, instinctual part of your brain – takes charge.
This shift to our primal brain is actually protective. It allows you to access your instinctual knowledge about birth and reduces anxiety and overthinking. Being in the primal part of your brain allows you to surrender to what is happening and ensures your body and baby work together in perfect unison.
Transition: The intensity peak
Transition is often the most intense part of labour, characterised by:
A burst of adrenaline that can create temporary anxiety - this is where you might say "I can't do this!" or "I want to go home now!"
Powerful oxytocin surges are helping to thicken the fundus - the thick layer of muscle at the top of the uterus, which in turn helps to push the baby downwards towards your cervix and into the optimal position for birth.
High endorphin levels for pain relief
Your pelvis widens, and the sacrum pushes up and back to make more space for your descending baby.
Many women experience what feels like a complete dissolution of self during transition. This is normal and temporary – it's your body's way of accessing the deepest instinctual knowledge needed for birth.
The birth: Trusting your body's wisdom
During the birthing phase:
Reflexes creates the natural urge to push.
Your body knows exactly when and how to push most effectively.
Your perineum gradually stretches to accommodate your baby.
You have natural instincts to protect your perineum by slowing your baby's exit.
As your baby descends through the pelvic pathway and out of your vagina, they are colonised by your beneficial bacteria, which is the start of the baby's microbiome.
The placenta: The final stage
The birth of your placenta is the final act of physiological birth. During this phase:
Your baby receives vital blood through the umbilical cord
The cord naturally stops pulsating as it completes blood transfer
Oxytocin, from bonding with your baby, naturally contracts your uterus
Your placenta separates and is born
“Research supports waiting at least one minute before clamping the cord, with many families choosing to “wait for white” – until the cord is completely empty. This helps ensure the baby receives all their rich, beautiful blood from the cord and placenta. ”
The bonding cocktail for connection
One of the most wonderful aspects of physiological birth is how perfectly designed it is for creating the mother-baby bond. During and immediately after birth, your body produces what can only be described as a "bonding cocktail" of hormones.
Peak oxytocin
At the moment of birth, oxytocin levels reach their highest peak in a woman's life. This massive surge serves multiple purposes:
It provides the final powerful contractions needed to birth your baby
It immediately switches your brain into "mother mode"
It creates intense feelings of love and protectiveness
It helps you forget the intensity of labour and focus entirely on your baby
The golden hour
The first hour after birth creates an incredible hormonal environment.
High oxytocin and prolactin make you feel deeply connected to your baby
Elevated endorphins create feelings of euphoria and accomplishment
Your baby's oxytocin levels also peak, making them calm and alert for bonding
Prolonged eye contact between you and your baby triggers even more oxytocin release
Protecting the hormonal environment
These bonding hormones are somewhat fragile - they can be disrupted by:
Bright lights and loud noises
Separation from your baby
Stress or feeling unsafe
Interruptions during the first hour
This is why many women instinctively want a quiet, dimly lit, private space after birth - their bodies are protecting this crucial bonding time.
When birth takes a different path
It's important to note that our brains have evolved so that even when birth doesn't follow the physiological path and women miss some of this natural hormonal cascade, the capacity for deep love and bonding remains completely intact.
Adoptive mothers, fathers, and mothers who needed medical intervention all bond beautifully with their babies. The physiological process is one pathway to bonding, but it's not the only one. Skin-to-skin contact, eye gazing, and quiet time together can help trigger these same bonding hormones regardless of how birth unfolds.
How you can support a physiological birth
If physiological birth is something you'd like to aim for, there are a variety of things you can do ahead of time and during your labour and birth that can go a long way to helping you achieve it.
Your environment
Research shows that certain conditions support physiological birth:
Privacy and safety: Feeling secure, unobserved, and supported allows the body to relax into the process.
Warmth, darkness, and quiet: These conditions support the primal brain, which allows you to tap into your intuition.
Minimal disturbance: Reducing interruptions helps maintain the hormonal flow.
Being patient
One significant finding from modern research challenges the traditional "Friedman's curve" developed in the 1950s, which suggested labour should progress with your cervix dilating at 1cm per hour.
We now know that:
Labour patterns vary widely between women
Less than 50% of women follow this "standard" timeline
Rushing labour can increase interventions and complications
“If you are having a hospital birth, it helps to stay at home for as long as possible. Most hospitals have strict policies about how long you are allowed to labour for after you’ve been admitted. Which means if you aren’t meeting the 1cm per hour “guideline”, you could be encouraged to have interventions to speed things along. All of which interrupts your own hormonal flow and can result in the opposite happening without medication. ”
Spontaneous vs. directed pushing
Your body has its own wisdom about pushing:
Spontaneous pushing:
Occurs naturally with contractions
Allows for better oxygen flow to the baby
Protects the pelvic floor
Adapts to the baby's needs for rotation and descent
Directed or coached pushing can:
Increase blood pressure and affect circulation
Interfere with the baby's natural rotation
Increase risk of tears and pelvic floor damage
Cause maternal exhaustion
Your perineum, your choice
Many women worry about tearing during birth. Research shows several factors can influence this:
Things that may increase the risk of tearing:
Being positioned on your back during pushing
Directed pushing
Use of forceps or vacuum
Routine episiotomy
Things that may reduce tearing risk:
Birthing in upright or side-lying positions
Warm compresses or water birth
Following your body's natural pushing urges
Allowing gradual stretching of tissues
“For healthy, first-time mothers, current Australian research shows that only 42% experience a vaginal birth without medication or instruments. This statistic isn’t meant to discourage – it simply reflects the reality we are living in today. If you want to have a vaginal birth without medication or instruments, it’s essential to have a solid understanding of physiological birth and educate yourself on who, where, and what will help you achieve it. ”
Knowledge is power
Understanding physiological birth doesn't mean rejecting all medical care. Instead, it can inform decisions about:
Choosing care providers who understand and support physiological birth.
Creating birth plans that work with your body's natural processes.
Recognising when interventions are truly necessary.
Advocating for evidence-based care.
Every birth is different, and every birth matters
Some women will experience straightforward physiological births, while others will need medical support to bring their babies safely into the world. Both experiences can be positive and empowering when women are supported, informed, and respected throughout their journey.
What matters most is not the type of birth you have, but that you feel listened to, acknowledged, and ultimately, in control of the choices you make in labour.
Understanding physiological birth gives you knowledge about your body's remarkable capabilities, which can be empowering regardless of how your birth unfolds.
Getting support
Whether you're hoping for a physiological birth or simply want to understand your options better, having knowledgeable support can make all the difference.
Birth doulas are trained to support the physiological process while helping you navigate any unexpected turns your birth journey might take.
“Remember: your body is designed for birth, you have choices in how you birth, and you deserve support that honours both your hopes and your needs.”
Every woman and birthing person deserves to feel informed, acknowledged, and confident during one of the most transformative experiences of their life.
Want to learn more about physiological birth? Read Rachel Reed’s book Reclaiming Childbirth as a Rite of Passage
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About Kelly Allen
My name is Kelly, and I’m an emerging birth and postpartum doula who is completing training at the Doula Training Academy. I service women and birthing people in the North Shore of Sydney, helping you enter and emerge from birth and the fourth trimester feeling physically and emotionally well.