Find Symmetry In Your Pelvis

My second birth prep tip is going to come out in 2 parts.  We have to talk a bit more pelvic anatomy and birth physiology before I can give you some tips on what to do!

Let’s start by talking a little bit about the actual “birth” process and the intricate series of movements your baby goes through to make it earthside.  For the sake of simplicity, we are going to talk about babies who present occiput anterior – the optimal positioning – and we’ll save the topic of different presentations for the subject of another post.

Ideally, baby starts with his back facing mom’s left side (left occiput anterior); baby engages and then starts it’s decent down into the pelvis with a little tucked chin (flexion). Baby continues to descend, internally rotating until the back of his head is facing mom’s front.  The baby’s neck then goes into extension as the head presents.  Once the head is out, the baby subsequently externally rotates to allow delivery of the shoulders.  (Click here if this is confusing and you want to see a picture).  Now the point of this post isn’t to understand all the details of this process – instead its to understand that baby is practically doing a gymnastics routine to come out.  With so many different movements needed (flexion, extension, internal and external rotation), no wonder some moms and babies have a challenging time with it.

Whoa.  Just take a minute and think about that process again.  Your baby is able to do all those position changes while traveling through your pelvis!  That is absolutely amazing!

So what can we do to make this process easier?

Baby and momma work best as a team during birth.  In order for baby to do his/her thing, mom needs to allow her body (and heart and soul!) to open.  And I’m going to argue that baby’s travel is a whole lot easier if your pelvis is symmetrical going into that opening.

Now what do I mean by a symmetrical pelvis?  Ideally, the bones in your pelvis should form a lovely stable and symmetrical ring – think more or less like a bony circle.  Again, I’m being simplistic with the anatomy, but the bony circle is made up of your sacrum in the back, and then the big wing bones (innominates) that wrap around the sides to join in the front at your pubic symphysis (click here for a picture).  When you put your hands on your “hips”, you are in fact on those big wing bones.  Of course there is actually a lot of variation in the physical bony shape of a woman’s pelvic ring – you might be a little more oval, a little wider, a little narrower, etc., but the bones themselves are usually pretty symmetrical from side to side.

However, keep in mind all the things your pelvis also has to do: it has to hold up the weight of everything attached to your spine and upper skeleton, and it has to transfer that weight to each leg in turn when you are walking. It also has to hold and protect a bunch of your internal organs. As a result, there are a lot of soft tissues that attach to that bony circle – you need a strong stable base both to sit and hang out, and to move.  I guess I’m really not just talking about the pelvis – I’m talking about the lumbo-pelvic-hip complex.  Like the team effort between you and your baby in birth, it’s actually a team effort between your lumbar spine, pelvis, and hip joints (and all their various muscles and soft tissues!!).  That team works inextricably together.

Phew.  We’re starting to get a bit technical here, so let me give you the take home anatomy message: your pelvis is a bony ring.  It has to work closely together with your lumbar spine and your hips in order to do all of the things it needs to do. As a result, there are a LOT of things that attach to the bones in this area: lots of ligaments, lots of tendons/muscles, and even internal organs (think uterus)…

Now a note about pregnancy and the hormone relaxin… The bony pelvic ring is directly held together by strong pelvic ligaments.  Those ligaments however, start to soften and relax as soon as the hormone relaxin starts circulating in your pregnant body.  That means your bony circle can start to move a little bit more than it normally does (it does have to open to let all those pounds of baby out!).  And since relaxin doesn’t really work on muscles, your pelvic ring is now going to start shifting and twisting just a little in response to the muscles and organs that are attached to it and pulling on it.

Oh wait – relaxin doesn’t relax everything??  No, it doesn’t.  (Want to learn more? Read this awesome post by Katy Bowman on relaxin).

And what does this mean for you? It means that if you have some muscles that are tight, or some scar tissue around your organs from a previous c-section or abdominal surgery, there could be some unbalanced forces pulling on your bony pelvic ring.  The sides of your ring (the innominates) may now be shifting and rotating in response to that.

That means your lovely circle may no longer be symmetrical.  And if its not, its harder for baby to navigate through (and sometimes it just plain hurts when you walk, or get out of bed or go down stairs).  Plus, baby needs every possible millimeter (I’m totally serious, millimeter!) to make those rotations during birth.  If he/she has to fight through uneven muscle tensions pulling on the ring, changing its shape and creating resistance, it’s a lot more difficult!  And probably more painful for mom.

So stay tuned this week for part 2 of this tip – how can you tell if you are asymmetrical and what can you do about it?