My birth story vs. science

newborn baby after labor and birth in third trimester

Am I in labor?

On a sunny November day in 2013 at 3 pm, I felt my first contraction.

Not wanting to over hype the situation, I casually said to my husband:

Me: “Just a heads up, I may or may not be in labor right now.”

We started timing each contraction as we had learned in our birth class.

Me: “Um, START!?.. maybe… and END!?.. I think.”

We considered my stats: each contraction lasted 30 seconds, arriving two minutes apart. These numbers could not be correct. Weren’t contractions supposed to start far apart and gradually get closer together?

We frantically googled. Debated. And googled some more. Had we really forgotten everything we learned in birth class?

Me: “Maybe they space out?”

Husband: “Maybe these aren’t contractions?”

Me: “Maybe you don’t know what the hell you are talking about?”

(Note to partners: don’t question a laboring woman about whether or not her uterus is contracting)


What are the signs of labor?

We have this image of a woman going into labor: casually going about her day when SPLASH! her water breaks, chaos ensues, they rush to the hospital and BAM, baby.

Nope.

Only 10% of women will experience such a clear indication of impending baby arrival. The rest of us have to guess.

Even when we guess correctly, the hospital is not the next step. There are many reasons to labor at home as long as possible, including a decreased likelihood of needing pitocin or birthing via C-section. In most cases, the hospital does not want you to walk in the door until you really need that bed. Active labor, impending baby — that’s the ticket to a labor and delivery room. As many new parents learn, and many doctors advise, the rule of thumb for judging active labor follows the 5–1–1 rule (5 minutes apart, 1 minute long, lasting for 1 hour).


Ok, so I’m in labor…

Those were contractions alright, and they came swiftly, every two minutes. To hell with 5–1–1. Time to rely on pain (or “pressure” as some like to refer to it).

Since I like to think of myself as a total badass with exceptional pain tolerance, I figured my labor was much further along than I let on.

We grabbed the hospital bag and hopped in the car.


But is “pain” actually a reliable measurement for labor progress?

“We think of active labor as ‘Pains plus Progress’ which usually means that contractions are coming at intervals of five minutes or less, are associated with discomfort for the patient, and with observable progress in cervical dilatation.” — Hendricks et al. 1970

When the frequency of contractions fails you, you rely on the pain aspect to make the judgement call of how your labor is progressing. The correlation between pain and cervical dilation remains a strong assumption across the birth community. Researchers have attempted to bottle this variable into a predictable model for labor progression to varying effects.

One research team went so far as to directly compare cervical dilation with documented “Numerical Ratings Scale” .

Less than 20% of labor pain scores were attributable to dilation status.

No surprise – this measurement might be completely subjective.

pain perception during labor and birth. The science of pregnancy and third trimester contractions

This science of pain perception. Seriously.


Labor Purgatory (aka Triage in Labor & Delivery)

Waiting to see if my situation granted me passage through the pearly sterile gates –

State your case — “Seriously, I’m in labor. #$%*! (contraction) See?!”

Present the evidence — “Here is my cervix, judge for yourself.”

2cm

What. The. Hell.

My dilation status hadn’t changed since an appointment earlier that day. One nurse gently noted that I would probably need to head home. Luckily my two-minute apart contractions garnered sympathy from another nurse who declared me in “rip roaring labor” and admitted me.


Signs of labor (as defined by research)

“Progress in labor is still assessed based on four main signs… Other than use of a tocograph, these signs have been unchanged since the 17th century.” — Higgens and Farine, 2013

The cervical opening has to widen to a whopping 10cm before the baby’s head fits safely.

Assessing labor progression relies heavily on this biological fact. Cervical dilation remains the sharpest tool in the doctor’s labor assessment tool kit.

cervical change in labor as an indicator of contractions and progress towards birth in the third trimester

Well, a human head does have to fit through there…

But there are several problems with relying on this tool.

One, it requires an internal exam — More internal prodding = greater risk of infection. Doctors will have to determine if the benefit outweighs the risk.

Two, it’s retrospective and relative — Progress between Point A and Point B depends on accurate measurements at both Point A and Point B.

Three, it’s subjective — Every inspector is different. The critical variable of point to point change may depend on whether both points were set by the same person.


Progress? Labor as a pass/fail test.

I’m not going to lie. Contractions hurt. Bad.

Time for medication?

I rode dangerously close to the edge of stalled labor. My thoughts spun — an epidural could limit my mobility; limited mobility could slow labor; slowed labor could result in C-section. I wanted to avoid that if possible.

No epidural for me.

(Note: I am not advocating against epidurals. I strongly believe that in some cases, epidurals can help take the stress out of the game of labor and help moms progress. I just didn’t think this applied to my case.)


And what if you fail the test of labor progression?

“…it may be necessary to revisit the definition of labor dystocia because recent data show that contemporary labor progresses at a rate substantially slower than what has been historically taught.” — ACOG

Labor dystocia, “abnormal” labor that stalls or shows limited signs of progression, accounts for over a third of all C-sections in the U.S. The zone between “normal” and “abnormal” often comes down to cervical dilation. If this diagnostic tool had a User’s Guide, it would be the Friedman Curve, a guide that classifies “abnormal” as labor progressing slower than 1cm/hour.

One problem — Friedman wrote his User’s Guide in 1959.

measuring labor progress based on old techniques for contractions and birth in third trimester of pregnancy

Ah, the 1950’s when pregnancy was glamorous and labor was fast

The Friedman Curve reflects female subjects in the 1950’s, when birthing mothers were younger and, presumably, thinner, and the epidural and oxytocin drip had yet to be employed.

Recent studies have emphasized that “normal” labor progression may be slower for women during induction, slower for women who receive an epidural, and simply slower for the average woman birthing in this century. Labor characteristics can change with age, BMI, a range of other parameters.

Every woman is different in life and labor. Imagine that.


The end is in site. Or is it?

6cm.

The end was in sight.

Contractions now came fast and hard. Imagine that feeling of getting slammed by a wave, rolling in the water for a minute, coming up for air, and getting slammed again.

Now replace each wave with a Mack Truck.

Nurse: “8cm. Almost there!”

one hour later

Nurse: “Now you’re a real 8!”

This classifies as the cruelest joke you could play on a laboring woman.

(apparently, I was 7cm at 3:30 but she failed to share the updated info)


Determining labor progress from the inside

“The digital examination remains the ‘gold standard’ for evaluation of the cervix in pregnancy; however, it has inherent variability” — Phelps et al. 1994

Cervical dilation is subjective. It is a snapshot. It can be affected by a contraction. It can be affected by the examiner.

When asked to palpate a series of “dilated” PVC pipes, obstetric nurses and doctors accurately determined dilation status HALF of the time.

Their level of experience (from 2–30 years) did not matter.

Give or take 1cm, and the “precision” jumps up to nearly 90%. Not bad.

As I can attest, though, a 1cm difference in the wrong direction can be heartbreaking.


…and then a baby

I hit 10cm 5:30am.

At 5:43, my baby took her first breath.

I had built a human and here she was.

baby born after contractions in labor and birth during third trimester of pregnancy

Look what I made!


As I reflect back, I can’t help but ask — Was my labor “normal”?

But perhaps I should ask –

What is “normal” labor?

and where and why do we cross into the zone of “abnormal”?

I’m a physiologist. I know the players: progesterone, oxytocin, prostaglandins. I have an over-the-top admiration for the placenta. I have a deep appreciation for the capacity of the uterus to expel a human being into the world.

I understand the human body. Yet, I did not understand my own body.

I am not alone. The concept of “normal” labor remains surprisingly vague, even in the medical community.

“Our inability to reduce the cesarean rate may be attributable in part to the incomplete understanding of a normal labor process” — Zhang et al. 2010

Assessment of labor progression using cervical changes is not an ideal tool but it is a relatively reliable tool.

In response to recent studies emphasizing the limitations of the Freidman Curve, ACOG adjusted their guidelines for defining labor dystocia. They now advise doctors to expand their concept of “normal” to allow for slower progressions before intervention.

A step in the right direction, but maybe it is time for a deeper tool kit? A more comprehensive picture, a sturdier starting point for big decisions on when to intervene.

What if we knew more about the physiology of pregnancy and labor?

Could more information about lead to better care, less invasive measures, improved birth outcomes, and lower cesarean rates?


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!

About the Author

Molly leads Content and Community at Bloomlife and edits the Bloomlife newsletter. She likes to puts her PhD in Physiology to good use by 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!

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