So you have hit your second trimester.
You’re starting to become aware of the fact that your body is changing, it’s getting weird, and there is a human growing in there. Suddenly that muscle that you’ve never given much thought to (well, maybe once per month) tightens, flexes, and adds a new sensation to add to your growing list of things you’ll experience during pregnancy.
You’ve just noticed the uterine muscle flex with a strange name: a Braxton Hicks contraction
Yes, my pregnant friend, you have little British man “with a cheerful expression” named John Braxton Hicks forever implanted into your pregnancy journey.
Braxton Hicks contractions vs. labor contractions
The American College of Obstetricians and Gynecologists recommends a few tricks to decide whether or not the sensations you feel are Braxton Hicks contractions or labor contractions. Understanding the timing of contractions – how far apart contractions are, how long each contraction lasts, whether they are regular and getting closer together – is one trick. When we interviewed members of the birth community about Braxton Hicks vs. labor contractions they also added their suggestions for distinguishing the two on your own. But, really the only way to know is to have a medical professional do a cervical exam. Labor contractions, by definition, are contractions that cause cervical change. Once the cervix starts to dilate, labor has begun and every contraction will start working its way to the end goal of getting that baby out.
As for those Braxton Hicks contractions, the running assumption is that they help tone and prepare your body for labor. The uterus is smooth muscle, its flexes are involuntary, like the heart. You cannot directly cause your uterus to contract, just as you cannot directly cause your heart to beat.
The pregnant uterus is truly an incredible organ: it will grow from the size of an orange to the size of a watermelon by the end of pregnancy, constantly changing and strengthening to prepare for its big moment as a baby expulsion machine. Perhaps the Braxton Hicks contraction is your uterus’ way of hitting the gym.
So, who the hell is Braxton Hicks and what is he doing in my uterus?
Now for your history lesson…
Dr. John Braxton Hicks gets the naming rights to those non-labor-inducing contractions you might feel throughout pregnancy because he was the first one to acknowledge that the magic and wonder of the pregnant uterus begins long before labor. In fact, before he came onto the obstetric scene in the mid- 1800’s, doctors believed that the uterus acquired a “new power to contract” only at the very end of pregnancy.
Not so, argued Dr. Braxton Hicks: “After many years’ constant observation, I have ascertained it to be a fact that the uterus possesses the power and habit of spontaneously contracting and relaxing from a very early period of pregnancy”
To jump to the end of his long road of uterine enlightenment, basically, Dr. Braxton Hicks spent nearly a decade putting his hands on many pregnant bellies, feeling the tightening and releasing of muscle flexing. When he realized that these patients did not have a baby on the way, he concluded that not only were these contractions spontaneous but also a natural part of pregnancy. In his descriptions, he noted that the contractions began as early as three months and increase in the second trimester. As Dr. Braxton Hicks notes: “most frequently it occurs every five or ten minutes, sometimes even twice in five minutes”
Although over 150 years have passed since he first described these non-labor-inducing contractions, the name “Braxton Hicks” has remained attached to them.
While you wait for the big day, think of that incredible muscle of yours preparing for her big moment to shine. (And my apologies if your contractions start taking on a British accent.)
The Pregnant Scientist is the alias under which Molly puts her PhD in Physiology to good use – digging into the scientific literature to share fun facts about pregnancy and parenting along with a few busted myths backed by solid research studies. Yay science!