"She's got good birthin' hips"!

“She’s got great birthing hips”! Have you heard that one before?
I see the following questions all over the net:
My hips are small, (insert measurement size) can I give birth naturally?
I know a women with really wide hips, and she ended up with a cesarean - what happened?
If you have big hips is child birth easier?
Can a woman's hips be too small for a vaginal delivery?

These are not dumb questions. The idea that a woman’s hip size has everything to do with her ease of birth is not a new idea. It’s been a way of thinking for centuries, and it’s hard to shake a long standing myth.

Let’s break this down. First we need a nice picture. Thanks to the 20th U.S. edition of Gray's Anatomy of the Human Body, originally published in 1918 - we can safely use the following pictures because they are now public domain.
You see those Micky Mouse ears on that pelvis? That is the ilium, and that is what we think of as the hip bone. Now the ilium comes in all different sizes. But the size of that iliac area does not have anything to do with birthing babies. When it comes to birthing, it’s the size and shape of that round hole in the middle of the pelvis that counts - but keep reading, because there is more to that than meets the eye. The main hole in the middle of the pelvis is called the pelvic inlet. This is where the True Pelvis begins. There is much more to the anatomy of the true pelvis, but I’m going to skip it, dare I bore you to death. The True Pelvis is what is measured during a medical assessment. Let’s pretend we are comparing two different women. The size of hip bones (the ilium and iliac crest) might be quite large, and in the other, they may be much smaller, but their pelvic inlet may be the same size. So we can’t go by the measurements of our waist - or the size and shape of our pelvis. But guess what else? Measuring the pelvic inlet is ALSO not a big help! Even with the help of x-rays, and presumably accurate measurements we cannot predict the passage of a baby through that pelvis. Here is it where it get’s *really* interesting.

What most people do not understand is that the pelvis is not an immovable structure. We tend to imagine the pelvis as something solid and some believe it is one giant bone. There are four joints that join different pelvic bones together. During pregnancy and labor the hormone relaxin softens and relaxes the ligaments that join the pelvic bones, allowing the pelvis to give and 'stretch'. Look at the above picture again - this time focus on where it says “pubic arch”. In between the two bones that meet there in the front lies a pad of cartilage. This is symphysis pubis. In some women there can become a pretty good gap there. It can be painful towards the end of pregnancy when this happens. However, my point is to show you that the pelvis can “open”. Look at the picture below and check out the ligaments attached to the various parts of the pelvis.


The story continues. There is one more thing we must consider. The baby. A baby’s head is made up of several bones - and they are made to overlap during birth. This is what causes molding. No one, not even a doctor, can tell a women how much the babies head will mold - or how much a woman’s pelvis will relax to accommodate that baby. The *only* way is to try it.

Women are told all the time that they have a pelvis that is too small. They end up with an automatic cesarean without a trial of labor, only to give birth to the next child - much bigger in size, vaginally. Just ‘google’ the many stories! The diagnosis of CPD (cephalopelvic disproportion - meaning babies head is too big compared to the size of the pelvis) is given out way to often - sometimes before the birth, and sometimes after a long labor followed by a cesarean. A long labor, and even a long pushing stage is not an indicator of a small pelvis/big baby. Often these same mothers give birth to their subsequent children who are much bigger. Labors stall for other reasons. This diagnosis gives women doubts in their bodies, and then they pass these doubts on to other women. A woman who is a size 20 and has a nice large hips is told she cannot give birth naturally to her 6 pound baby. She tells the woman who is a size 5, with ‘smaller hips’, and then this poor women doubts her ability to give birth. Next thing we know, we have women measuring their hips, and wondering if they will have a harder or longer labor - and they are scared of a baby bigger than X pounds.

I write this because there are so many women out there questioning their ability to give birth. I don’t know if doctors are afraid of lawsuits, or what - but why is there such an increase in this ‘problem’? I’m just really glad that there are women out there that go ahead and say “YES I CAN!”. It is because of these women that we know that this diagnosis is often wrong -perhaps to error on the safe side of a lawsuit.