What is physiologic (“natural”) birth and how to have one.

Sep 21, 2021

Reading time: 23 minutes 


What is a physiologic birth, and how is it different from other descriptions like “natural” or “vaginal” birth? Why might you want to have a physiologic birth? And how can you maximise your chances of having a safe physiologic birth without unnecessary interventions?


Mama, if you're wondering the answers to these questions (or if you just need a handy, easy-to-read explainer to enlighten a family member or friend), then you're in just the right place! By the end of this blog post you'll know the what, why and how of physiologic birth - and I hope also you’ll share some of my passion for this beautiful, life-changing rite of passage.

If you prefer to learn by listening rather than reading, you might like to check out the podcast version of this blog post, right here.

Now before we jump in, I prefer not to use the term “natural birth” for a few reasons that we’ll talk about below – so I’ll be using the term “physiologic birth” in this blog post to describe a birth that’s driven solely by the natural biological processes of the mother’s and baby’s bodies, without any pharmaceutical or surgical interventions.

Oh, and fair warning before we get started – I get VERY excited about physiologic birth! First, because it changes women’s lives (I’ve experienced this myself, and I’ve witnessed it in many other women who’ve had physiologic births. Once a woman has experienced the power of undisturbed birth, she is unstoppable). And second, because it’s stunningly beautiful. The way women’s and babies’ bodies work together in perfect synchrony in an undisturbed birth is nothing less than magical.

And mama - if you'd like some guidance about how to prepare for your own safe and empowering physiologic birth from a trained doula and someone who's experienced it herself, you might be interested in my free download, The Four Things You Actually Need to Know to Prepare for a Physiologic ("Natural") Birth.

Ok, now let’s jump into it…

What is physiologic birth?

A physiologic birth is one that’s driven solely by the natural biological processes of the mother’s and baby’s bodies. In other words, it’s a birth that doesn’t involve any kind of pharmaceutical or surgical intervention.

I prefer to use the term “physiologic birth” over other terms such as “natural birth”, because “natural birth” can mean different things to different people. For example, some women consider any vaginal birth as a “natural” birth, whether or not it involves drugs or assisted delivery with forceps or vacuum. (There’s nothing wrong with that, by the way – it’s just not what I’m talking about here.)

You might also hear people use the term “undisturbed” birth – that’s another term for physiologic birth, and I sometimes use that too.

Personally, I like the term “physiologic birth” because it has a clear definition that comes from midwifery research, so its meaning is unambiguous, and it doesn’t carry any moral judgement. In a physiologic birth:

  • labour begins spontaneously (it isn’t induced or augmented by drugs)
  • the conditions surrounding the birthing mother promote effective labour (we’ll talk about this more below)
  • the baby and placenta are born vaginally
  • the birth of the placenta happens naturally, without medication
  • the mother and newborn are kept together and given skin-to-skin contact immediately after birth, and
  • breastfeeding is initiated early after the birth of the baby.[1]

In my experience as a childbirth and parenting educator, most of the mamas I work with (not all, but the vast majority) want to birth their babies physiologically, without drugs and interventions. And research supports this preference - midwifery experts agree that this type of birth is more likely to be safe and healthy for mothers and babies because it doesn’t involve any unnecessary intervention that would disrupt their normal bodily processes.[2]

What’s more, the vast majority of women are capable of having a physiologic birth. Research from around the world tells us that around 85% of women are capable of giving birth without interventions. Some people (myself included) believe this number is actually much higher. For example, at one community in the United States known as ‘The Farm”, where women give birth at home with the support of midwives, 98.6% of women have unmedicated vaginal births without any interventions.[3]

But despite all this, physiologic birth is an extremely rare event in “developed” countries today. Statistics aren’t readily available, but we do know that in Australia in 2018, less than a quarter of women birthed their babies without the use of pharmaceuticals to induce or augment their labour.[4] Within that small group of that 20-25%, the percentage of women who birthed their babies without any further interventions such as pharmaceuticals or instrumental delivery is likely to be very low.

So why this discrepancy?

To understand why so many women don’t end up birthing physiologically despite their preference to do so, we need to understand exactly how physiologic birth works, and what conditions women need to be able to birth physiologically. That means a quick tour of our human evolution – so buckle up, fellow nerds!

Humans have evolved to be very good at birthing babies

In our modern world of gadgets and comfortable houses, it’s easy to forget that we’re actually animals. To be exact, humans are large mammals. And when it comes to birth, it’s really helpful to remember that our bodies have been evolving over hundreds of millions of years to become very, very good at reproducing.

Dr. Sarah Buckley, an expert on physiologic birth, says:

“Giving birth is an innately instinctive act, hardwired into our brains and bodies through millions of years of mammalian evolution, and designed to ensure the best possible outcomes for mothers and babies.”[5]

This statement, that birth is designed to give mothers and babies the best and safest possible experience, isn’t just wishful thinking – nothing less than the survival of our species depends on the safe and efficient birthing of the next generations. As elder midwife Jane Hardwicke Collings reminds us:

“Why would Mother Nature develop a process, upon which the survival of the human species depends, that was flawed and dangerous?”[6]

Our ancestors evolved over hundreds of millions of years to reproduce as safely and efficiently as possible. This physiological reality is our ‘mammalian blueprint” for birth. I like to think of it as Mother Nature’s grand design – a kind of map that gives us all the information we need to be able to birth our babies safely.

What is Mother Nature’s map for safe and efficient birthing?

Like all animals, our bodies need certain things to be able to function effectively. To breathe, we need access to clean air. To fuel our bodies, we need access to nutritious food and clean water. And to birth our babies, we need to feel private, safe and lovingly supported.

And just like all mammals, if human women feel private, safe and lovingly supported, we’ll produce exactly the right symphony of hormones at exactly the right moment to birth our babies as safely and efficiently as possible.

As Dr. Sarah Buckley explains, Mother Nature prescribes a very specific “cocktail of hormones… to aid birthing mothers of all mammalian species.” These all-important hormones of birth are:

  • oxytocin, the hormone of love
  • beta-endorphin, the hormone of pleasure and transcendence
  • the catecholamines, epinephrine and norepinephrine (adrenaline and noradrenaline), the hormones of excitement,
  • and prolactin, the hormone of tender mothering.[7]

These hormones work together in myriad complex ways to ensure both mother and baby have the smoothest possible transition from gestation to lactation, and from womb to world.

So, why do so many births require high levels of interventions?

Ok, so if our incredible bodies are so good at producing this perfect cocktail of hormones to help us safely birth our babies, why are so many women’s births characterised by pharmaceutical and surgical interventions?

Ah, now we come to the all-important point. 

While our bodies produce exactly the right hormones to efficiently birth our babies in the right conditions (when we feel private, safe and lovingly supported), our clever bodies are also very good at shutting down labour in conditions where we feel watched, unsafe, and disrespected.

Further, when we add synthetic drugs to the finely choreographed symphony of hormones that a woman’s labouring body produces, we very easily throw off the hormonal conditions that are needed to birth her baby physiologically.

This isn’t a fault of women’s bodies. On the contrary, it’s another part of our brilliant evolutionary design. Why would any animal give birth – a highly vulnerable state – in an environment that feels unsafe?

This is why such a high proportion of births in our modern time end up requiring high levels of interventions. When we interrupt the delicate balance of birthing hormones by making a woman feel unsafe, we throw off the hormonal cascade that Mother Nature has prescribed and inadvertently make birth less safe. We create a need to intervene, which otherwise may not have been there.

Dr. Sarah Buckley says,

“An optimal hormonal orchestration provides ease, pleasure and safety during this time for mother and baby. Conversely, interference with this process will also disrupt this delicate hormonal orchestration, making birth more difficult and painful, and potentially less safe.”[8]

Let’s think back to some of those other physiologic functions that our bodies do every day. Take digestion as an example. Most of the time, your body is very good at digesting food, taking the nutrients it needs, and passing the rest as waste. But have you ever noticed that when you’re stressed or tired, your digestion can be a little “off”? This doesn’t mean that your body is a failure because it isn’t digesting its food perfectly. It’s a sign from your body that it isn’t receiving the optimal conditions for digestion.

Let’s think about sleep as another example of a normal physiologic process that our bodies do without us really thinking about it. But what happens when you’re stressed, in an unfamiliar environment, or your partner is snoring loudly in your ear? Sleep is a physiologic process, but when conditions aren’t optimal, we don’t sleep as well. That doesn’t mean humans are really bad at sleeping, it just means we need to create the right conditions so that we get the best sleep possible.

It’s the same with birth.

So let’s talk a bit about the “optimal” conditions a woman needs to birth her baby.

What do women need to birth their babies safely and efficiently?

A really easy way to understand the conditions women need to birth is by comparing birth to sex. That’s not such a crazy stretch as you might think – actually, the hormones that are necessary to birth a baby are exactly the same as the hormones necessary to have an orgasm.

Birth and sex are very much related. Legendary American midwife Ina May Gaskin is known to say, “the energy that gets the baby in is the energy that gets the baby out”.

“Sex is the central fact of reproductive behavior from conception to birth. If the sexual aspect of labour and birth is ignored, it will often work against progress in labour. Of course, the converse is also true – the application of sexual energy can make labour more effective and less painful without any use of medication.”[9]

Take a moment to think about the conditions you’d need to feel comfortable enough to have an orgasm. Would you want to be in a brightly lit room, where strangers in white coats keep walking in and out, nurses continuously interrupt you and your partner to take measurements of certain bodily functions, and you’ve been given a time limit?

Or would prefer to be somewhere familiar, like your own home, where you feel safe and private? Where you know you have all the time in the world, and won’t be interrupted? Where you can light a few candles if that’s your thing, put on some music if you feel like it, move around freely, make as much noise as you like?

Birth is just the same. For birth, as with sex, women need to feel private, safe and lovingly supported.

Is physiologic birth really better than birth that involves interventions?

Now that we understand what physiologic birth is and the conditions women need to have one, you might be wondering why would you want to have a physiologic birth? Is physiologic birth really better than medicated or surgical birth?

The shorter answer is: absolutely.

The long answer is: absolutely, and I’d need a whole other blog post to do justice to why physiologic birth is the safest and healthiest way for most mothers and babies to birth! 

Stay tuned for another blog post soon, where I’ll go into lots more detail about the risks associated with unnecessary interventions in birth, and the benefits of physiologic birth.

For now, let me throw to the expert, Dr Sarah Buckley, one last time:

“Undisturbed birth represents the smoothest hormonal orchestration of the birth process, and therefore the easiest transition possible; physiologically, hormonally, psychologically, and emotionally, from pregnancy and birth to new motherhood and lactation, for each woman. When a mother’s hormonal orchestration is undisturbed, her baby’s safety is also enhanced, not only during labour and delivery, but also in the critical postnatal transition from womb to world.”[10]

I’ll give you just one example to illustrate the beautiful, complex, miraculous ways that physiologic birth sets mothers and babies up for the best possible transition from gestation to lactation, and from womb to world.

Let’s talk about what happens in an undisturbed birth during what’s sometimes called “the golden hour” – the time immediately following the birth of the baby.

  • After baby is born, mama will pick her baby up and instinctively place their head close to her left breast. This universal behaviour places baby as close as possible to mama’s heart, and on her rising and falling chest – helping the newborn to regulate their cardiovascular and respiratory systems during the huge transition from womb to world.
  • Mama’s chest will automatically change temperature, either warming up or cooling down, to help baby regulate their temperature (yes, really! How cool is that?!).
  • Mama’s nipples smell like her amniotic fluid, and this familiar smell attracts baby to begin to move towards the nipple.
  • As baby crawls up towards mama’s nipple, the movement of their legs on her stomach helps to massage mama’s uterus, stimulating contractions. This helps the uterus to return to its pre-pregnancy state, and reduces the risk of postpartum haemorrhage.
  • Baby’s first breastfeed also stimulates oxytocin and uterine contractions, further reducing the risk of postpartum haemorrhage.
  • Baby’s final descent through the birth canal stimulated a massive dose of oxytocin (the hormone of love) in both mama and baby – setting them both up with a feeling of euphoria and love, and helping with early bonding.
  • That same descent through the birth canal stimulated a spike in adrenaline in both mama and baby, making baby more awake and aware in the hour immediately after birth than they will be again for weeks. This heightened awareness gives baby the opportunity to closely study mama’s face (it’s not an accident that newborn babies can see only about as far as mama’s face when they’re at her breast), scanning her features for the very first time so that they’ll be able to recognise her.

Can you think of a more beautiful, perfect, symbiotic design? (All of these processes, by the way, are disrupted in a birth that involves interventions and in which baby isn’t immediately placed on mama’s chest for skin-to-skin contact).

The short video below gives you super quick glimpse of a newborn breast crawl - I challenge you to watch it and not be awed by the beauty of an undisturbed golden hour.


How can you maximise your chances of experiencing a physiologic birth?

Now that we understand what physiologic birth is and the conditions women need to experience it, it’s probably already becoming clear to you why so many women in “developed” countries today don’t experience a physiologic birth. The overwhelming majority of women in “developed” countries give birth in hospitals – and the simple truth is that hospitals are not optimal environments to make women feel private, safe and lovingly supported.

Where are women more likely to feel private, safe and lovingly supported?

Well, you’ve probably already guessed it – the ideal environment for most women to birth safely is at home. And research consistently confirms that women are much more likely to experience a safe physiologic birth if they choose to birth at home with the support of a private midwife.

Recent research in Australia, for example, found that women who birthed at home were six times more likely to experience a drug and intervention-free vaginal birth than women who birthed in hospital. Not only were home-birthing women much more likely to experience a physiologic birth, but there were no differences in the health outcomes of mother and baby between the two groups.[11] 

For most of us who've grown up to fear birth, this can be a challenging concept to take on. When we think of birth, we think of hospitals. And for high-risk pregnancies, hospital can indeed sometimes be the better option. But most pregnancies aren't high-risk. And the research consistently confirms that for women with low-risk pregnancies, home is the safest place to give birth.

Knowledge is power. 

So to return to the question we asked at the beginning of this blog: what do you need to know to give yourself and your baby the best possible chance of birthing safely and without unnecessary interventions? 

  • You need to understand what physiologic birth is, and the conditions women need to birth physiologically (private, safe and lovingly supported).
  • And you need to know that you’re much more likely to experience these conditions, and therefore much more likely to experience a safe physiologic birth, if you choose to birth at home with the support of a private midwife.

And don’t forget to grab your free copy of my guide, The Four Things You Actually Need to Know to Prepare for a Physiologic ("Natural") Birth!

Until next time, stay wild mamas,

Jess xx



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