Anti-Natal Care: The Due Date Fallacy

More on Estimated Due Dates (EDD)

The “standard algorithm” to calculate gestational due date is called Naegele’s Rule. It was formulated in 1850.

Fast forward to 1990 for the first ever update to the due date calculation, following some studies showing that Caucasian women deliver most often a good 8 days after just about everybody else, and babies of first-time mothers almost always take an extra week over a multiparous woman’s gestation length. Now there’s a Mittendorf calculation, named after the guy who realized there’s a racial and experiential difference in gestation lengths.

(What that means for me: if you’re white and it’s your first kid, you take your EDD from Naegele’s Rule and add 8 days. Brilliant.)

There’s more to it than that, actually; there’s a software model that can be used to take 16 of factors into account like smoking, maternal age, and even college education, to reach a gestational prediction that’s twice as accurate as Naegele’s Rule.

But even with all the tech-mology we’re throwing at this, women still only have roughly a 29-37% chance of delivering in the 40th week! And the Mittendorf study actually shows the average length of human gestation is 41 weeks + 1 day.

I understand there are statistically more risks in carrying babies longer than 42 weeks. The placenta has an expiration date, and the baby’s going to have his first poop at some point and you don’t want him to do it inside the womb. These are aspects of what’s known as “post-maturity syndrome”.

But if the predictions we’re using aren’t actually improving fetal outcomes, then we’re most likely causing undue anxiety and unnecessarily early inductions in a significant number of pregnancies where there should have been no concern about post-maturity syndrome at all. Indeed, researcher Nichols study that “70% of women classified as postdate in his study were incorrectly dated.”

Add on the fact that only a small percentage of pregnancies carried beyond 42 weeks result in babies born with post-maturity syndrome — 95% of babies born at gestational ages between 42 and 44 weeks are born safely and without incident — and a picture emerges of a cultural (ours) in which habitual early induction is committed ritualistically, unscientifically, and with only the shakiest of indications to support it.

I wouldn’t be so bothered about all of this but for two big issues, one personal and one societal. Obviously I have a vested interest in doing a natural, non-medically-induced birth, and that means — much to my ire — getting “permission” from the medical establishment to carry this child until he’s good and ready to come out, on pain of not being admitted to the hospital of my choice if I choose to continue my pregnancy “post term”.

(St. Luke’s will not accept any pregnancies past 41 weeks + 6 days; if you are in their care, they will schedule you an induction on or before that day — whatever They calculate that day to be.) Yes, I’m doing a home birth, but my midwife is beholden to the medical world in many ways, one of them being the policies of your back-up hospital in case something goes wrong at home.)

But when I read the attitudes and stories of women who post in the forums on (my sort-of-guilty pleasure for the past 10 months), in which the dominant attitude seems to be very much pro scheduled inductions and C-sections, that’s when I get really mad. Because I know that these women have been guilted and lied to, misled about the supposed equivalence of these procedures to a natural birth, made anxious about the long-term effects of vaginal delivery (incontinence is not irreversible OR inevitable!), and encouraged to think of their gestation length as a fool-proof, scientifically calculated finish line…

…when really, the medical establishment has been routinely using a demonstrably faulty technique from 1850 to decide pregnancy outcomes.

This article, referencing several medical studies on human gestation length and perinatal outcomes, was enormously helpful in writing this blog post:

Calculating Due Dates and the Impact of Mistaken Estimates of Gestational Age

And this Canadian study on post-term pregnancies provided a lot of useful statistics:

Recent Trends in Fetal and Infant Outcomes Following Post-term Pregnancies

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Anti-Natal Care: A Gross Recalculation

[This is the second in a short series of posts I'm calling "Anti-Natal Care", telling the story of my interactions with St. Luke's Hospital and Medical Center just before and shortly after the birth of Calvin.]

and now for something completely different

When last we left me, I was annoyed and worried about being 1 week overdue and possibly predisposed to a gestation length of 43 weeks. But I was going ahead with the hospital schedule of having two fetal non-stress-tests between 41 and 42 weeks, mostly just to follow the hospital’s protocol but also to provide useful information to my homebirth midwife, Maria, if there happened to be anything wrong.

So I called the hospital. Hilarity ensued.

After leaving the message with my favorite nurse-midwife, Julie, I got a call back from her within about 2 hours. (That’s not bad.) What she had to say threw me for a loop; the first thing she did was ask me why I thought I was at 41 weeks.

I said, “September 24th is the due date we’ve been using since our first appointment at St. Luke’s. It’s based on conception date, which I’m pretty darn sure of.” I hadn’t ever calculated my own due date; I let Julie do it, and trusted the number even more when we went to Maria and she pulled the same result.

“Hmm, okay,” she said. “So, actually, I reviewed your charts and ultrasounds and ran it through a much more sophisticated algorithm, and it looks like your due date ought to be September 29th.

Me: “What!? Um. Ok…?”

Keep in mind I’m hearing this on September 30th, a solid 6 days after my given Due Date, and 7 days before They kidnap me and pump me with pitocin, unless I go into labor naturally before then.

There’s an algorithm, Julie explains, that they can use to evaluate the trajectory of the baby’s growth using the two standard ultrasounds (9 weeks and 20 weeks, for me). It’s based on Crown-to-Rump Length or CRL in the first ultrasound, and several body measurements in the second trimester ultrasound, as I read in this paper.

Ultrasound can be used to estimate age, by comparing measurements against average fetal growth curves. Crown-Rump Length is measured in the first trimester. Later, they measure the length of the femur, abdominal circumference, head circumference, and diameter across the head (bi-parietal diameter).

Anyway, so what Julie was effectively telling me is, according to the hospital, I was only one day late at the time I talked to her. Apparently, St. Luke’s considers this the most accurate calculation, and will structure its interpretation of whether you are pre- or post-date around that.

The ramifications immediately elated me. I can go to 43 weeks.

Of course, I birthed Calvin a week ago today. He’s perfectly healthy, and the stress of the medically mandated finish line is lifted.

But that just makes the whole Due Date Thing even more confusing! Did I go into labor roughly “on time” or a week late?

And hey, St. Luke’s? I came in on September 25th to “pre-admit” myself to Labor and Delivery to make sure I had an easy time of transferring if the need arose. I’m in your system. If the ultrasound due date calculation is now your gold standard for labor admissions, why did it take leaving a message for a smart, savvy nurse-midwife, who was only prompted by my asking for a fetal non-stress test, for this calculation to be run at all?

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Anti-Natal Care: Maternal Stress Test

[This is the first in a short series of posts I'm calling "Anti-Natal Care", telling the story of my interactions with St. Luke's Hospital and Medical Center just before and shortly after the birth of Calvin.]

On Wednesday, September 29th, my midwife recommended I get a fetal non-stress-test (NST) to check on the baby, as Friday would mark the 41st week of my pregnancy. I left her office that afternoon and tried to set up the appointment at St. Luke’s. Since I know that this test has to take place in Labor & Delivery, I aimed there first.

Wednesday, 4pm: Attempt to get through to Labor & Delivery.

“Welcome to St. Luke’s Medical Center. Por instrucciónes en español, presione el número dos. Please choose from one of the following options. For the Women’s Center, press 1…”

Menu system doesn’t offer option to reach this department. Decide to call the Women’s Center to see if they can transfer me.

“The Women’s Center is now closed. Please call back between the office hours of 8am to 4pm, or press 1 to leave a message with our answering service.”

Ok… Guess I’ll leave a message. Press 1. Ringing.

“Hello, this is St. Luke’s Hospital?”

“Uh, yeah, I’m trying to make an appointment to get a Fetal Non-Stress Test…”

“Oh, you must have been transferred here because the lines were busy. This is the Answering Service.”

“Uh, okay. Could you transfer me to Labor and Delivery?”

“Hm. I don’t think I have that number.”

“Uhhh ok..? Is there somewhere I can leave a message for someone who can set up this test?”

“Oh, ok, I’ll transfer you.”

Click… Ringing

“Welcome to St. Luke’s Medical Center. Por instrucciónes en español, presione el número dos. Please choose from one of the following options. For the Women’s Center, press 1…”

Thursday, 8am: Calling the Women’s Center again.

“Hello, this is St. Luke’s Women’s Center, can I help you?”

“Yeah, I need to set up a Fetal Non-Stress Test for Friday.”

“Oh, well, you need a medical provider to evaluate and request one for you.”

“Um, okay.” (Do NOT make me come in for an appointment just to make another appointment!)

“Do you want to leave a message for someone here? Or should I just put Any Available?”

“Oh. Well I was working with Julie Vivalda, but any available is fine if she’s not around.”

“Ok, I’ll leave the message.”


[In the next post, I get a call back from Julie.]

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Our Son Calvin Arrives

Calvin Chaos emerges! (Click to go see more photos)

Well well well! Surprise of surprises, little George kicked his way out this weekend. (And we didn’t name him George — that was just his “womb name”.)

Calvin Chaos Myer-Most was born at our home in San Francisco on Sunday, October 3rd, 2010, at 7:24 am. He weighed 7 pounds and 8 ounces at birth, and measured 20 centimeters in length.

I labored with him for roughly 20 hours, from 11am Saturday through 7am Sunday, and then spent 24 minutes pushing him out. Labor felt like an infinity, all-of-time and no-time at once. Pushing was a welcome shift to lucidity, and easily the most incredible thing I’ll ever feel my body do.

Right now I am listening to his father, Josh Myer, snuggle down with him for a nap on the bed. Calvin’s making loud squeaks as he flails a little and figures out what his limbs are supposed to be feeling. Josh squeezes him close and he settles down a little.

Grabbing little snatches of time to write is — as most parents will no doubt understand implicitly — really hard right now. So even though I desperately want to write the whole birth story ASAP as well as finish off the little backlog of posts from before labor, I’m keeping this one short.

Oh, by the way, you can follow @CalvinChaos on Twitter. He’s had a few thoughts already. His mom and dad are @nthmost and @xek.

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Overdue or Simply Owing to Innocuous Abnormality?

I’m breaking my own moratorium on prenatal blog posts due to some new information I got from the hospital today when I asked for a fetal non-stress-test appointment. My homebirth midwife, Maria, had recommended I do so as soon as possible, since as the night swings us over to October 1st, I’m now exactly 1 week past my due date — 41 weeks pregnant — according to my due date of September 24th.

In the prenatal world, due dates are the all-important arbiter of progress, scheduling, health, and — most importantly — danger. Risky outcomes for fetuses reach a nadir at 38 weeks and then slowly rise every day as the pregnancy progresses. Today, 42 weeks is considered the absolute limit in length of a healthy pregnancy.

I’m actually less than convinced about the 42-week safety barrier, at least as far as my own situation is concerned. Here’s why.

The following may be classified “too much information” for some people because it’s very plain talk about sex and lady things. Proceed at your own risk and don’t come whining to me or my mom about something icky you accidentally read. Yeah, you heard me.

Read the rest of this entry »

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Pregnancy and Karate

My midwife asked me at my last appointment what my pain coping techniques would be. I said, “martial arts”. Later, my mom and her boyfriend gently chided me for thinking I’d ever experienced anything like the sort of pain I would experience at birth.

Ok. Would you like to describe to me the kind of pain it’s going to be? Would that help? I think it wouldn’t. I think it’s going to have be experienced to be believed and understood, and when you feel it, you’ll just have to find some tools within yourself that match what needs to be done to get through it.

There are techniques that martial arts teaches that give you tools to deal with extreme situations of many kinds. Pain is just one kind of extreme experience.

I’ve had a lot of extreme experiences in my life as I’ve studied Goju-Ryu Karate-Do, Koryu Iaido, Wu-style Tai Chi, and a bit of yama-bushido with waterfall training. That last one is a doozy. Try standing under a mountain waterfall in early December, holding your balance on slippery rocks for at least 5 minutes while heavy, freezing cold water hits your head and your body basically goes into shock at about the 2.5-minute mark.

I digress. Tonight I found a blog post done by a woman at 1st kyu rank in Goju-Ryu karate regarding how it helped her in labor.

What’s particularly empowering to me is her mention of Sanchin kata, because that was the first thing that came to mind when I read about “breathing the baby down”.

Her blog seems to be down right now, so I’m reprinting the whole thing from Google cache here.

This is Google’s cache of It is a snapshot of the page as it appeared on Sep 12, 2010 17:51:31 GMT. The current page could have changed in the meantime.

Text-only version

Pregnancy and Karate – My Experience

I start this article with the glad tidings of the birth of our daughter, Emma Louise Grant, on the 14th September 2000. For those whom did not realise, this is why I haven’t been training since January – no, I hadn’t emigrated or been abducted by aliens!!

I took the decision to rest and be cautious on realising I was pregnant, despite the fact that many women do continue their karate training to full term. I applaud those who do achieve this – personally, I was too tired after work and I did not want to disrupt the dojo’s training routines, despite reassurances from my sensei, Andy Barker, that this would not be the case! Having said this, Goju Ryu Karate did have a role to play in my pregnancy. I found the whole experience of training and taking gradings had equipped me quite uniquely for the rigours of labour!

I am currently first kyu, which has meant that gradings over the last four-five years have become more demanding physically and mentally. They have tested my personal metal to achieve higher standards and to push my body to the best of its ability. The mental focus required for all kata and particularly the technique of breathing in Sanchin kata enabled me to address the issues of relaxing and controlling my breathing during labour – an aspect of karate which I’m sure can be applied to many other situations, such as stress at work or confrontations…

The relaxation and breathing techniques from karate helped enormously in alleviating the labour pains. I was also able to overcome the additional birth complications which I experienced by drawing on the same determination, focus and spirit required to succeed in my gradings.

I feel Goju Ryu Karate provides unique skills not attained from most team sports; it is more than just a way of keeping fit, I think it is about developing yourself from the inside spiritually and mentally; about pushing mind and body to your own perceived boundaries and beyond. The sense of achievement at the end of a grading – at all levels – supports this. I might also add that there is a wonderful sense of achievement and relief at the end of having given birth too!! When you see what you have laboured for – quite literally!!

Now Emma is with us, I hope to return to training soon and I would like to thank all our friends at Sheffield Hallam Dojo for their support over the last 9 months. I hope this article shows how much karate influences all aspects of our lives and is an encouragement to other expectant mothers amongst us!

Kathleen Grant
Sheffield Hallam Dojo

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Beginning of the End of Pregnancy

This is the last post you’ll see before the baby’s here.

For the past 5 days or so, I’ve been:

  • spacy, ditzy, unable to focus
  • insanely tired after just a 4 or 5 block walk
  • getting unmentionable pains of a certain variety (though I go ahead and mention them anyway) at an increasing rate of frequency
  • feeling the baby’s head slip further and further down (increasing those certain pains)

So I’m going to finish off the handful of blog posts I started at various points this summer, some tonight, and some the next night, because I think this is the beginning of the end.  I’m going to back-date them so that this post stays at the top, so if you want to read more from me, look slightly farther down on the page.

I’m going to yoga in the morning; maybe it’ll be my last class.

My mom’s here. She’s going to stay as long as it takes to see her first grandson.

Oh yeah, and happy birthday to me!

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Resolved and Unresolved Pregnancy-Related Ailments

Nausea: Eat something starchy.  Rice Krispies with almond milk is now my major comfort food.

Heartburn: Eat pineapple. Fresh, not canned. Kombucha — really sour homemade stuff — also does the job, but moderation is key (about 2 oz should do it).

Side Pain while Sleeping: It’s the weight of the belly, apparently. I got relief by putting a beat-up old feather pillow under me, horizontally, filling the space just under my ribs down to my hips. So my side isn’t raised up more than half an inch, but my belly is lifted and supported by the bulge of feathers in front of me (sort of like what happens with these wedge pillows). It’s worked very well, and when I don’t set myself up like this, the pain comes right back.

All-Over Rashless Itching: Saved for the end because it really deserves its own section.

No cure yet, only ameliorations. The best solution for me has been to take a hot shower followed by allowing cold breezes on my uncovered, un-towelled-off body. That usually buys me 20-30 minutes to get to sleep.

What absolutely doesn’t help:

  • anti-histamines (whether OTC or prescription; tried Allegra for 7 days, no effect whatsoever, didn’t even make me drowsy)
  • lotions, oils, or sprays of any kind (most just made things worse)
  • trying to fall asleep early (the itch comes on whenever I’m relaxed… so if I relax early, I itch early too)
  • scratching (relief lasts for maybe 5 seconds)
  • acupuncture (though I didn’t give it a full try; only made it to 2/3 sessions)
  • “the tea” — an herbal infusion all the midwives and yoga teachers suggest as the pregnancy panacea.  (I drink it anyway, but only because it’s a tasty way to get water and minerals in me.)

What helps a little:

  • deep stretching about an hour before bed (seems to reduce intensity & frequency of itches, but very variably)
  • getting strenuous exercise throughout the day
  • being really, really, REALLY fatigued (e.g. staying up to 4 or 5 AM… ahem…)
  • taking a hot shower (relief for about 20 minutes, sometimes long enough to fall asleep)
  • standing naked in a cold, breezy room (the cold overrides the itch, apparently)

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Hormonal Link to Rashless All-Over Itching

Even If I’ve given up on a solution for the all-over rashless itching I experience on a near-nightly basis, I definitely haven’t given up on researching its possible origins.

Lately I’ve found reason to believe that my nervous system may simply be responding to the highly elevated estrogen levels endemic to pregnancy.  It’s also possibly a function of the ratio of hormones at any given time.

I have to think about the fact that the itching severity seems to be cyclical. I wish I’d been keeping a log of this symptom (along with a few other data points that might be correlated), because then I’d know whether this pattern IS cyclical or if my brain just wants to fit my fuzzy data to a pattern.

Well, hindsight is 20/20.  The best I can do is try to figure out where I probably am with my hormone levels, based on the norms, and build from there.

Hormone Levels During Pregnancy – A bunch of somewhat interactive graphs showing average hormone levels in pregnant rats over the course of their pregnancies.

As you can see in the graphs, estrogen and progesterone are both exceedingly high throughout pregnancy, until the last week in which progesterone apparently falls right before birth so as to allow oxytocin to induce contractions (this is hypothesized but not confirmed).

Wikipedia on Progesterone:

  • In addition progesterone inhibits lactation during pregnancy. The fall in progesterone levels following delivery is one of the triggers for milk production.
  • A drop in progesterone levels is possibly one step that facilitates the onset of labor.
  • And: “Whether a decrease in progesterone levels is critical for the initiation of labor has been argued and may be species-specific.”

Here are some anecdotes to explore the hypothesis of there being a hormonal cause to all this needless, diagnosis-and-treatment-resistant itching.

  • In this forum, women on fertility-induction plans complain of certain types of itchiness in a pattern much like mine (worst in palms, feet, crotch, ankles) whenever they are taking progesterone.
  • Women with Salicylate Sensitivity in this forum are concerned about the blocking of progesterone by phytoestrogens (e.g. in soy), because progesterone seems to keep the itching (one of their endemic symptoms) at bay.

Finally, just to be uber-sciencematific, here are some Yahoo Questions in which the asker seems to have a very similar problem to me. Of course no one has a useful Answer.

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On Biking and Balance with Baby

As soon as you become pregnant, you find that the whole world suddenly has an opinion about what’s best for you. Yet strangely, that advice is hardly ever coupled with encouragements to listen to your body and learn to tell when you’ve reached your limits, or whether you just need to put in a little preventative maintenance.

The pregnancy party line about biking is this: you may expect to keep biking until about 6 months in or so, but certainy not beyond that. Why? Because, the experts say, your balance will be compromised — best just to stay off it.

I read one woman’s list of “things she wish she’d known during pregnancy”, finding an item to the effect of:

“Balance: don’t use it! It will be gone and you’ll risk falling over and hurting yourself all the time.”

Bah! Balance is a muscle that atrophies; use it or lose it.

My mom encouraged me early on to practice balance. She said when she was pregnant, she would make sure she could still put her socks on standing up.

I’ve been doing the same. I also do sets of 16 to 24 roundhouse kicks or side leg lifts without letting my foot touch the ground between each one. And while prenatal yoga tends to play it safe with us big-bellied ones, steering clear of crescents and bows, there are enough poses requiring balance in multiple dimensions to keep those neurons and muscles responsible for stabilization well exercised.

Because that’s it, isn’t it? Balance is a thing to be exercised. Just like biceps, logic, flexibility, and your sense of timing for making soft-boiled eggs.

So the idea of balance just sort of vanishing into thin air as a matter of inevitability is both misguided and harmful. Yes, everyone’s experience will differ greatly, which is why I say practice balance to the fullest, but “your mileage may vary.”

Only you can prevent yourself from toppling over, and that means understanding your body’s limits and tolerances — and then pushing on them whenever possible.

So when the hospital or the interwebs say you should be giving up the bike before the third trimester or even eschewing it throughout the pregnancy, they’re doing so under the assumption either that you won’t be practicing your balance, or that balance is not something you’ll have control over.


It’s supremely telling that the only nurse-midwife I had at St Luke’s who was genuinely encouraging me to keep riding my bike is now contracting with a midwife to have her own child be born at home. (My midwife, Maria, I think!)

You know want I think her direct advice would be?

Exercise, do what feels right, and learn your own limits, because no one can decide them for you. You have control over what you’re able do — whether you happen to be pregnant or not.

(And as for me: 38 weeks and still biking!)

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