Pelvic Shape, Life Style and Childbirth

The World Health Organziation recommends a C-section rate of 10-15%. Quite a big difference to the 30-40%  which is the reality in most of the Western world. 

Failure to progress in labour is the number 1 reason for unplanned C-sections. From a diagosis of failure to progress, it can go three ways:

1) a number of interventions are made to speed up progress and those often result in more interventions, with a C-section at the end
2) the woman is wheeled right into the operating room 
3) skilled, supportive and patient birth attendant(s) help the woman to progress using a variety of non medical interventions 

Whether it goes one way or the other largely depends on the type, personality, knowledge and skill of the care provider(s), the place of birth, how well informed the mother is of her choices in labour and birth, how well the informed choices are actually put into practice and what kind of relaxation and movement techniques the mother may have learnt in preparation for birth. But is there more to it maybe?

Research confirms that women of today have slower labours than women in the 1950s.

And I suspect that women of the 1950s had slower labours than the women of the 1900's. 

Has our lifestyle something to do with "our" failure to progress?
Are our bodies maybe not what they could be?

Our bodies were designed to birth babies, naturally. Women have done it for eons (with the occassional bad outcome, of course).

What is going on????

What Dr Kathleen Vaughun observed and questioned around 1917 in her paper called "The Shape Of The Pelvic Brim As The Determining Factor In Childbirth"

"In the Carnagie Trust Report for 1917 we read of easy labours and large families among the Highland women who, bare-footed, haul in the nets with the men, follow the plough, and engage in field work, and mention is made by local authorities of the tinker women who live in tents and whose custom it is to be delivered safely and rapidely by the roadside before any doctor or nurse can be called to assist. Strong contrast, this, to the maternal mortality rate and the infant death rate to be met with in cities such as Edinburgh and Glasgow. In England we still have our gipsies and canal-boat women, with their large families and easy and safe confinements, and yet our maternal mortality rate shows no decrease in the last twenty years, and industrial towns like Swansea, Cardiff, Barnsley, Bradford and Rochdale head the list with their maternal death rates.

The fundamental cause of difficulty is obvious: that for some reason the child's head and the mother's pelvis do not fit, and delayed and difficult labour is the result: bruising of soft parts, exhaustion of the mother, risk of sepsis - all these things follow on this primary failure of adaptation. Is the foetal head too big or the maternal pelvis too small?"

So she wanted to shed some light on this and consulted Sir Arthur Keith who was a Scottish anatomist and anthropologist. It was his belief that the heads of the race were getting larger amongst civilized people but the pelvis of the same people didn't seem to keep pace. Dr Kathleen Vaughun got his permission to examine and measure the pelvises of dead people at the Royal College of Surgeons.

She considered two factors: the unyielding pelvic brim of the mother and the yielding fetal head which needs to pass through the brim.

Naturally, she found out quickly that pelvises come in a variety of shapes so she concentrated on the parts of the pelvis that are relevant for childbirth which is the available space for a baby to pass through.

She measured along the ilio-pectineal lines: a ridges on the left and right ilium and pubic bone showing the brim of the true pelvis.

How did the pelvises vary?

She writes that "the European-English women, Frenchwoman and Russians were flattened from the back, having the long diameter transverse."

Then she found pelvises of the Andaman Island females specimens, the Sikh woman, South Australian and who she calls the "Negress" (ugh) - and those had a perfect circle where the transverse (side to side) and front to back diameter were of equal length.

She concluded that "the more primitive the habits of the life the more circular the pelvis".

"There should be in all men and women, …, a mobility of this (SI joint) joint and a constant change of pelvic inclination as the subject walks, runs, sits, stands, or crouches, and the immobility of this joint leads to serious changes in pelvic shape. (...)

In England the still soft pelvis is bent by long sitting at school, and this is not counteracted as it should be by the proper action of the sacro-iliac joints, which should be used daily, if only during the acts of defaecation and urination. The wearing of high heels also limits and cramps their movement, the body weight is thrown forward on to the arch of the foot instead of the heel, the pelvic angle is altered, and the back unduly hollowed to preserve the balance. That these facts are the real explanation of our increasingly difficult maternity is clearly seen when we compare them with condiditions where motherhood is still natural and easy.“

She further concludes that birth is a natural function and is easy and safe when the head fits the pelvis. The missfit is due to the lack of front to back diameter and this is caused by wither rickets (a childhood bone disorder that is almost unheard of these days where bones soften and become prone to fracture and deformity mainly due to a lack of Vit D and malnutrition – also why women in developing world suffer major birth complications often resulting in fistula) and, more relevant for today, the disuse of SI joint before the age of 14.

What other childbirth experts note more recently

I have Jean Sutton's and Pauline Scott's little booklet on "Optimal Fetal Positioning in which they outline factors that influence the occipito posterior position of the baby (where the baby's spine lies against the mother's spine, aka sunny side up or the one with lots of back labour). This is one of the physiological culprits for lack of labour progress. Here goes:

1) sofas, armchairs and car seats that encourage slouching

"When a pregnant woman sits in a modern arm chair or sofa, her pelvis tips backwards and so does her "passenger". (...) Her 'passenger' has no alternative but to lie towards the back of posterior part of her pelvis. (...)"

2) women of today don't do tasks around the house that involve forward leaning (like scrubbing the floors on hands and knees or farm work)

3) abdominal muscles that are too tight

"The pregnant woman who has tight abdominal muscles produces a sharper angle between her lumbar spine and her pelvic brim. This can encourage her baby towards an OP position, compared to the pregnant woman whose abdominal muscles are more relaxed."
(They are referring to the tucked pelvic posture from exercising the superficial abs too much.)

And a quote from biomechanist Katy Bowman

"The first thing to understand is, while pregnancy may seem like an unnatural position for your body to be in, it is quite natural actually. 
What makes it feel so awkward and possibly uncomfortable is the extreme loading done on an unbalanced, rickety frame.  I once bought a cool table from the Goodwill, even though it didn’t balance quite evenly.  It wasn’t that big of a deal in the store, but once I brought it home and tried to put stuff on it, the lack of stability became more of a functional issue.  It’s the same thing with all of you out there with chronic low back and pelvic pain, feet that are flattening, birthing canals that are narrow, and abdominals that are splitting (diastasis recti).  These are not issues of pregnancy, but issues of pregnancy on an unstable frame."
click here for more

The issues of our unstable frame (our body) stem from what we do or don't do with our bodies: too much sitting, too much repetetive movement, too little walking, too little variety and not enough frequency of our movements.

What you can do to exercise our SI joint (hint: get a BUTT), to make our pelvic shape more optimal for natural childbirth and to create a strong frame to carry pregnancy well

- stop slouching, sit less, walk more, wear flat shoes, learn how to squat properly
- read this and, if it intrigues you, click all the links that lead you to more reading
- if you are in Ottawa, come to our Prenatal Alignment Class or book a private Restorative Exercise session
- if you live somewhere else, find your local Restorative Exercise Specialist and attend class or book a private session

FOR FUN, watch this video of a prenatal exercise class in 1939 with exercises designed by no other than Dr Kathleen Vaughun.

Here am I at 28 or so pregnant doing a partner squat with my colleague Jillian.


- hold onto eachothers forearms and sit back into squat

- keep knees over your ankles and untuck you pelvis (stick your butt out) but don't overarch your back (keep your sternum pointing down)

- hold for a little while to give your hamstrings and butt a workout

P.S. What is the plural of pelvis?



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