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Where is the pelvis? The Importance of an Upright Pelvis in Birth

We often ask, “Where is the baby?” in a pregnant woman, but even more important is the question “Where is the pelvis?”  A new vision is urgently needed in birth.  Anatomically, babies are supposed to be born “out the back.”  In the diagram here of a woman on a bike, note that even in an upright position, small movements in posture affect the angles between the spine and the pelvis.  The arrows depict the direction in which the baby will be born. Today, most women are lying on their backs birthing their babies “out the front” which makes birth more difficult.  Anatomically, babies are supposed to be born “out the back.”

Even though we are not always aware of it, our bodies are always in constant motion with the heart beating, lungs breathing, and blood vessels carrying precious nutrients throughout the body and excreting what is not needed.  Gravity plays an important role in these processes.  Even a newborn needs to start learning anti-gravity positions to start the process of being upright and eventually creeping and walking.  The human body wants to be upright and active to function efficiently.  This includes birthing a baby.

We have gravity because of the dynamic equilibrium of the Earth moving around the sun. The speed with which this happens creates a centrifugal force that balances the gravitational force between the Sun and the Earth.  Gravity is so important to our very existence that astronauts in space need to exercise at least two and a half hours each day to give the body a sense of weight-bearing.

It is much easier and more comfortable to defecate in upright positions.  In the same way, it is easier and more comfortable to birth our babies when the pelvis and the organs within it are in upright positions.  Just picture a section of a water hose held upward at either end.  If this was the birth canal, imagine how much more difficult it would be to have to push the baby up against gravity to be born – yet this is exactly what most women do!  They are lying on their backs with knees pulled up and out making birth much more difficult.  How much easier it would be to turn around onto hands and knees or on knees leaning over a birthing ball or pillows on a chair, or lying sideways with the pelvis shifted forward, or even standing, allowing gravity to be their friend!

Standing, holding onto a rope and taking weight off the feet offers a very important aspect of giving birth not much talked about.  This is the effect of stretch receptors feeling the stretch upward on the upper body.  It is helpful in labor to have the forces going up balancing the forces going down.  It is believed that stretch receptors actually play a part in signaling a woman’s body to go into labor. Gravity plays a role when giving birth as well.

The way in which a woman in labor postures herself, is likely to affect the way the entire birth may go.  This is because the baby has more space in which to move when the pelvis is tipped forward in upright positions.  This allows the baby to move into advantageous positions to move and rotate through the pelvis and helps to prevent dysfunctional labors.

The pelvis lying down appears very different than the upright pelvis.  Even slight angles forward make a huge difference in terms of how the baby comes out as can be seen in the diagram.   Lying down flat on the back, a woman is lying on her sacrum.  The sacrum needs to move forward and backward which actually changes the available space in the superior and middle inlets.  In an upright position, the pelvis is already, normally in an oblique position, tipped forward.  Add to that the help of gravity assisting the baby in coming down, and a laboring woman moving her body, changing positions, all of which can make labor easier. At the same time, the uterine muscle, itself, is working hard to contract down to help the baby move into the pelvis.  If a woman allows gravity to assist this process  by keeping herself upright or at least with her pelvis forward, she is likely to have a shorter and easier labor.  Of course, add to that the presence of a doula or birth companion so she feels safe, and the experience can be much more positive.

If you have seen women in labor lying down, you may notice something interesting.  This has to do with the Rhombus of Michaelis.  These are a bundle of nerves by the low sacrum that have a role to play in labor.  The baby in an OA or Occiput Anterior position, will flex or bend his head to put pressure on these nerves just before the moment of birth.  The mother will reflexively respond by lifting up her left hip and knee with a slight puffing out in her low back. This opens up the birth canal for birth so the baby can be born “out the back.”  With an epidural, you can see women trying to lift up this part of the back with none or limited ability to do so.

So which way do you want to birth your baby? With gravity or without gravity?  It is as simple as that!  Become familiar with upright, forward leaning positions for labor.  Try them out while pregnant so they become familiar to you.  Then know that these are optimal positions for your labor.  But if you need a rest, sidelying with an anterior or forward pelvis is also a good option.