Childbirth Physiology

Birth is the Mount Everest of bodily functions for any mammal. It is likely the most you will ever ask of your body. Humans are different from other mammals, birth is more challenging for our species. Our hips are more narrow especially in comparison to our nearest relations and as a species we combine being bipeds with the fact that our babies also have larger heads.

Birth has evolved over millions of years to gracefully accommodate both the natural selection of walking upright and the development of our brain’s frontal lobe. They may not be particularly roomy but a woman’s pelvis and birth canal have more than enough space to get the job done.

The uterine walls expand as your baby grows and by the time of labor they are relatively thin, even so, they can still mightily contract during labor and are more than capable of pushing even a big baby through an open cervix and out the vaginal opening.

Your vagina is able to open, its size and shape will shift to accommodate its contents. A penis, a tampon, a speculum or a baby, it opens and accommodates them all, for this is what a vagina is designed to do.

Labor involves movement and the shape-shifting of your organs which in turn allow the baby to descend through the birth canal, a process that features prolonged physical sensation and considerable effort.

While birth is a physiological function akin to your heart beating, your lungs breathing, and your intestines digesting, birth is something more than any of these more common bodily functions.

Unless we physically exert ourselves or develop health issues we seldom even notice the involuntary movements of our breath or of our beating hearts. Being a human living in the 21st century I would imagine you notice “digestion” more often than you would like.

You can train your heart and your lungs to accommodate the exertions that come from running in a marathon. Both organs are made of smooth muscle tissue which means they are primarily controlled not by cognitive thought but by your Autonomous Nervous System. You can apply conscious thought to speed them up or slow them down but without their constant involuntary movements we soon collapse and die.

You “train” these smooth muscles tissues by making the conscious decision to begin running and to keep running. The consequences of this decision means that you don’t just strengthen your thigh muscles you condition your heart and lungs as well.

A practice of slow deep breathing while enduring strenuous prolonged physical activity will keep your heart steady as it pumps blood to your straining muscles and the consequence of this is that your body will be unable to pump stress hormones throughout your system.

You are therefore training your whole body to work as an effective, efficient running machine. The successful marathon runner has a system in place that helps her stay in the race, mindfully preparing herself with the coping mechanisms that will allow her strength, discipline and endurance.

Your uterus is also made out of smooth muscle. You do not have voluntary control over its actions, your ANS runs the show. So except for your “period” you may never notice your uterus and if you aren’t prone to menstrual cramps you may not even think of it on a monthly basis.

Your uterus literally takes center stage during your pregnancy and the birth of your baby, it is impossible to ignore.The catch is that you can’t condition your uterus, you can’t take it out for a bit of contraction interval training or for a trial run of birth.

In this way Labor is kind of like getting up and deciding that your very first run is going to be the Pittsburgh marathon. But the burning crampy feelings you get in your thighs after a bit of running are exactly the same as the muscle fatigue your uterus is experiencing after a couple hours of labor.

So if you understand how to deal with muscle fatigue in a voluntary muscle like your quadriceps then you understand how to deal with muscle fatigue in an involuntary muscle like your uterus.

The key is remembering that contractions are the healthy pain of a healthy muscle working, only difference is that your thinking brain can control your legs- that is a voluntary movement and your uterine contractions are an involuntary function of the ANS.

You can voluntarily decide to drop out of a race but your body is going to birth your baby regardless of how you react to the sensations of birth.

So if things like slow steady breathing works to keep your blood pumping efficiently and stress hormones at bay during the long miles of a marathon then the same technique will work its magic during the prolonged physical sensations and the effort of Labor.

According to Ina May Gaskin, the “big” secret is that your body is better able to accomplish this task when you can imagine or picture it happening. You need always to remember that mothers who are afraid tend to secrete hormones that delay and inhibit birth. Hormones play a huge role in the regulating and timing of birth.

This is true of all mammals and is a part of natures design. In our distant past this ability helped us escape predators and allowed us the ability to get out of harms way. Birth is best if left undisturbed, but getting out of a burning building first remains priority one.

The rhythmic contractions of the uterus as propelled by the ANS will thin and pull back the cervix and then push the leading part of the baby down through the lower part of the pelvis.

But let’s not get ahead of ourselves. Next up the early phases of labor.

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