What natural childbirth advocates like Milli Hill don’t know about the neurophysiology of pain could fill a book — or several.
Hill recently wrote The myth of the painful birth – and why it’s not nearly so bad as women believe. It is a typical paean to ignorance and disrespect — implying that childbirth pain is culturally conditioned and due to lack of support.
Milli Hill and her natural childbirth colleagues don’t know much about history. They don’t know much biology, either.
At the moment, we simply do not know what birth would be like for women if they were given more positive messages and went into labour feeling strong, confident and capable. We simply don’t know what it would be like if all women were given one-to-one support from a midwife they really trusted, or if we created birth rooms, even in hospitals, that were dimly lit, homely and uninterrupted.
Since the beginning of time women have described childbirth as agonizing because they always gave birth in hospitals with bright lighting and unsympathetic male physicians. Oh, wait! Up until very recently all women gave birth in dimly lit, homely surroundings complete with one-to-one support from a midwife.
Obviously Milli Hill and her natural childbirth colleagues don’t know much about history. They don’t know much biology, either.
When it comes to sport, we all seem to understand just how much negative thoughts can affect your performance both physically and mentally. We know how powerful a confident attitude can be. Perhaps it’s time to consider that with birth, things are no different.
Wrong! The neurophysiology of sports pain is very different from the neurophysiology of childbirth pain.
Let’s start with the most basic difference. Most sports pain is somatic pain whereas labor pain is visceral pain. The distinction is critical.
According to Wikipedia, somatic pain can be deep or superficial:
Deep somatic pain is initiated by stimulation of nociceptors in ligaments, tendons, bones, blood vessels, fasciae and muscles, and is dull, aching, poorly-localized pain. Examples include sprains and broken bones. Superficial pain is initiated by activation of nociceptors in the skin or other superficial tissue, and is sharp, well-defined and clearly located. Examples of injuries that produce superficial somatic pain include minor wounds and minor (first degree) burns.
The pain of crowning, when the baby’s head stretches the vagina, is somatic pain, but the pain of uterine contractions is visceral pain:
Visceral structures are highly sensitive to stretch, ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting. Visceral pain is diffuse, difficult to locate and often referred to a distant, usually superficial, structure. It may be accompanied by nausea and vomiting and may be described as sickening, deep, squeezing, and dull.
The neurophysiology of the visceral pain of uterine contractions is very different than that of somatic pain. Most importantly, visceral pain activates the autonomic nervous system, the nerves which control the automatic functions of the body like heart rate and blood pressure. In other words, visceral pain — unlike somatic pain — has a variety of effects that go beyond the conscious sensation of pain. These include elevated heart rate, elevated blood pressure, nausea and vomiting, and profuse sweating. Visceral pain — whether it originates in the heart, the gall bladder, or the uterus — is often perceived as “sickening.”
In her piece, Hill claims:
…[E]ven in ‘the nightmare labour from hell’ – 36 hours of contractions coming thick and fast – she can still expect to be without pain for around 60 per cent of the time.
That statement might be true if we were talking about the limited nature of somatic pain. If you poked someone with a pin for 20 seconds out of each minute they would feel fine for the 40 seconds that you aren’t poking them. But it’s definitely not true for visceral pain like uterine contractions. Even when the pain recedes the elevated heart rate and blood pressure as well as the nausea, vomiting, sweating and overall sickening sensation often do not recede completely before the next contraction begins. So women in labor do not spend most of the time feeling well except for intervals of pain. They spend most of the time feeling awful.
That has important implications for the philosophy of natural childbirth. The pain of uterine contractions is very different from the pain of athletic endeavor. The idea that the pain of labor is socially conditioned is nonsense; we can identify the receptors and trace the pain pathways. Most importantly, the pain of uterine contractions triggers a cascade of neurological responses that are not under conscious control.
No amount of support in labor is going to prevent women from having a profound physical response to uterine contractions that goes far beyond the sensation of pain itself. In contrast, an epidural, which blocks the neural pathway by which uterine pain reaches the brain does more than merely eliminate the pain. It also eliminates the autonomic nervous system response. When the pain goes away, the nausea, sweating and sickening feeling usually go with it.
The bottom line is that natural childbirth advocates promote a philosophy based on wholesale ignorance of neurophysiology. Childbirth pain doesn’t come from lack of support or lack of confidence. It comes from pain receptors, neural pathways, and the activation of the autonomic nervous system. Telling women about the excruciating pain doesn’t set them up to fail as Hill would have us believe. It’s simply telling them the truth.
