Pregnancy Biomechanics

If you are reading this, chances are you are either pregnant, plan to be or have been at some point in your life. Pregnancy brings lots of changes to the body; some that are obvious and some not so obvious. With all the changes throughout the pregnancy, we see changes in overall biomechanics. Some modifications in daily life are necessary to ensure tissues are not over stressed or strained during pregnancy. We will be discussing those here.

The biggest change in pregnancy is the slow transition of a change in center of gravity. As the baby grows, the belly will expand both up and forward. The expansion forward is what most people are aware of because you can visually see it happening in time. As the uterus expands upwards though, this is something more intimate that the mother is acutely aware of. Kicks and flutters that start near the low belly, then head towards the belly button and the joys of getting a stern kick to the ribs about 10 minutes after eating or downing a cup of cold water. As the baby settles into an optimal position, (hopefully- but not always!) there is also movement in the lower belly an abdomen as the baby gets bigger overall and the room at the top starts to get tight. I have been amazed each pregnancy at the feeling of the baby rotating the head back and forth in the pelvis along with the feeling of hiccups, which are much lower in the belly.

The progressive expansion upwards also brings changes to the intestines and vital organs. In

the beginning stages of the pregnancy before it is outwardly obvious to anyone but the mom, there is a shift in the lower intestines that can bring uncomfortable gas and bloating. Mom's also feel this as a slow decrease in room for the lunges to take a full deep breath or becoming short

of breath much easier, feeling like their stomach can't handle as much food at once because even though they are so hungry, they get fully so fast and the infamous acid reflux which can come on with and without babies born with hair-no matter what anyone tells you. We will touch base here again when we talk about the biomechanical changes a little later.

As the belly expands forward, this is what everyone else will be seeing and discussing. Every person is going to carry differently and show at different rates. First time mom's almost always "pop" later than a subsequent pregnancy. Some of this is the fact that the body remembers. But a lot of it is due to the fact that most of this tissue has never had this much external force put on it to stretch it and expand.

Along with the belly/abdomen changing, there are also changes occurring in the pelvis as things progress. Some of this is the body readying itself to birth the baby with the assistance of the hormone Relaxin entering the body in the final trimester which will expand all of the joints in the bony pelvis. There are other biomechanical changes happening in the pelvis before this though. The uterus lives in the pelvis and has a tissue called the round ligament anchoring it to the pelvis on each side. So as the uterus grows upwards, there is a pull and tug on the round ligaments that can occur differently on one side versus the other. We will discuss this again later as we discuss how mom's biomechanics can play into possibly preventing the baby from getting into a good position. As shifting occurs in the center of gravity, the female pelvic stabilizing tissues start to modify what they are doing to help maintain movement for everyday life. Hip positioning has to change as the thigh will start to have less space to get into a full depth squat as it is running into the expanding belly. Mom's also find themselves having to change their positioning due to not having enough room to complete daily tasks like washing the dishes at the sink because the belly has gotten so large there isn't room to reach forward and complete the task as normal. They rotate themselves to one side or the other which modifies all of the tissue of the pelvis and supportive structures surrounding the hip.

The last big change to discuss is the expansion of the breast tissue. For some, this is one of the first obvious signs of pregnancy. For others, the change is not as drastic. Any increase in breast size during pregnancy will add extra stress to the joints of the upper and middle back. We see this not only in pregnancy but also with breast implants. Biomechanically, there is more weight pulling the body forward which puts a strain on the tissue on the back- especially in the upper back. The other thing that is changing with breast size is the slow outward expansion of the rib cage. If you have been pregnant, you will notice yourself wanting to use the clasp setting on your bra at the larger size. Many women think this is just due to the breast tissue itself expanding when a lot of this actually is due to the rib cage widening overall to make room for the baby.

So how do all of these changes really affect our biomechanics?

The number one thing to discuss is maintaining proper positioning of the rib cage over the pelvis aka posture. Because there is so much stressing the tissue of the rectus abdominis

forward, it can pull the body into hyperextension in the lower back. Think of this as a sway back look. The classic position to catch women late in pregnancy in is a wide base of support, toes rotated out, belly drawn forward, lower back hyperextended and the pelvis shifted forward in front of the feet. This disrupts the proper positioning of the diaphragm over the pelvic floor. The diaphragm will continue to contract downward towards the abdominal contents and because in the sway back position creates an angle of the diaphragm forward, this creates even more midline stress on the rectus abdominis.

Ever heard of the abs separating in pregnancy? The big scary diastasis recti people talk about?

Diastasis recti, DR for short, is separation of the mid-line core at the connective tissue called the Linea Alba which runs from the bottom of the sternum to the top of the pubic bone. It creates the midline attachment point for the core and you can think of the middle line of the six pack abs. DR occurs in pregnancy but can also occur with all other improper use of the core. See our previous blog post about the core to get a better understanding of this concept. DR is more commonly seen in pregnancy due to an increase in overall abdominal contents, i.e. the growing uterus and fetus, along with improper biomechanics as the pregnancy progresses. The sway back position we just discussed above can also feed into a great separation towards the end of pregnancy which we should be working to minimize.

It is a lot of work to maintain a more optimal position in pregnancy. There is a bowling ball that is getting progressively bigger pulling the belly button forward. In order to maximize biomechanics and minimize pain and symptoms in pregnancy, ensuring that we are not feeding into these stresses is ideal. Some exercises are going to create more midline stress and if they are not able to be controlled as the pregnancy progress and should not be performed. Oblique work to connect the bottom of one side of the rib cage across the belly button to the opposite hip with help to minimize the amount of separation that can occur in the case of DR. Breath work is also extremely powerful in late term pregnancy and throughout the early phases in the post partum journey. If we take a more optimal diaphragm breath, we are activating the muscle more fully and intentionally which can help to maintain better positioning overall.

Ensuring a proper position of the ribs over the pelvis also gives the baby the most optimal space to allow the tissues to expand evenly as the pregnancy progresses which will promote the most ideal position for birthing the newborn. If the body is consistently twisted through this area- think crossing the legs and hiking the hips when in a seated position- it can create an uneven stretch on the round ligaments of the uterus along with having one side of the abdomen tighter or shorter than the other. This can feed into issues of the baby getting "stuck" in a suboptimal position. We highly recommend patients to be seen throughout their pregnancy to prevent any myofascial restrictions from building up contributing to this.

The final thing to discuss about biomechanics is listen to your body. Our bodies are really incredible and the changes that occur during pregnancy are both fascinating and extremely natural. Listen to what your body is telling you. If you have a particular type of exercise planned for the day and get started but it doesn't feel great, modify and doing something that feels better. There are a lot of unknowns within pregnancy, especially if you have never experienced it before. Find someone you feel comfortable talking to about the changes and the things that have become scary to do during pregnancy. I have always said no question is a bad question. Listen to what those around you are saying but also go with what makes the most sense to you overall because no one knows your body better than you do. The more you practice this during your pregnancy, the easier it gets in the parenting days of life.

If you are pregnant, postpartum or plan to become pregnant and want more information about anything you read here, feel free to reach out to the office for questions. With a proper examination and observation of functional movements, our office is here is help with optimizing biomechanics not only in pregnancy but also just in life overall.

Best in Health,

-Dr. Kylie Rabe

Chiropractic Physician

Mother of 3 ❤️