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« Hospitals Can't Handle VBACs? Then What Can They Handle? | I Had Shoulder Dystocia Once. Will It Happen Again? »

Can My Doctor Really Predict Shoulder Dystocia?




“I’m 36 weeks and the ultrasound said that my baby is going to be nine pounds! My doctor says I might need to get used to the idea of having a c-section because the baby might grow too big for me.”

“My doctor scheduled me a cesarean because the ultrasound said that the baby is already ten pounds and he says I am at risk of shoulder dystocia.”


As the cesarean rate around the world skyrockets, women are turning to message boards on a daily basis with the same story: late-term ultrasound, recommendation of cesarean for big baby, doctor says shoulder dystocia might occur if I deliver this baby vaginally, I scheduled the c-section. Occasionally women will question others on the message board about the validity of their doctor’s shoulder dystocia prediction abilities.

In addition to asking other women to share their experiences, reading a page from a recent obstetrics textbook might be helpful. The following quote is from page 140 of  Munro-Kerr’s Operative Obstetrics  (2007) by Baskett, et. al.:

Unfortunately, attempts to find factors that will accurately predict shoulder dystocia and allow a practical prevention strategy have been unsuccessful. Most of the antepartum risk factors have fetal macrosomia as the underlying theme. Many of these risk factors are common, while the condition they predict, shoulder dystocia, is not. Furthermore, the risk of serious fetal injury associated with shoulder dystocia is rare. The hope that ultrasound prediction of fetal weight and more detailed ultrasound measurements such as shoulder width would provide an accurate level of risk have been unfilled. Indeed, for the macrosomic fetus clinical estimation of fetal weight is as accurate as that predicted by ultrasound. Even if one could predict fetal macrosomia accurately, it would be of limited value. About 95% of infants weighing over 4000 grams will not have shoulder dystocia. It has been suggested that elective caesarean for fetuses weighing more than 4500 grams would reduce shoulder dystocia and fetal injury. A decision analysis model has shown that this strategy would be both clinically and cost ineffective; it was estimated that to prevent one permanent brachial plexus injury 3695 caesarean sections would be required. Furthermore, the majority of cases of shoulder dystocia occur at fetal weight less than 4500 grams.

Thus, both the antepartum and intrapartum risk factors lack sensitivity and specificity. Having said that, there are individual cases with cumulative risk factors such as maternal diabetes and estimated fetal weight > 4250 grams which may be best delivered by caesarean section. A combination of factors such as clinical fetal macrosomia with a protracted late first stage of labour and slow descent in the second stage requiring assisted mid-pelvic delivery may dictate that caesarean delivery would be more prudent.


Refusal of a doctor’s recommendation of a prophylactic cesarean without suffering coercion and deceit should be regarded as a fundamental right of the pregnant woman.



Related Posts:

I Had Shoulder Dystocia Once. Will It Happen Again?

ACOG on Fallibility of Obstetric Judgment and Mode of Delivery



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Reader Comments (7)

Kathy, do you use Google alerts? Set one up for "c-section ultrasound big baby." The big baby scare is way more pervasive than anyone realizes, I think. Telling a woman her baby might get too big and she might need a c-section is looking more and more like just a routine part of prenatal visits.

June 18, 2009 | Unregistered CommenterJill--Unnecesarean

Great post - I just wish more women were up to the "refusal" part.

That Google alert is a good idea! Right now I just have it set up for a few basic phrases (like "birth", and do you know how often wingnuts are talking about Obama's birth certificate? People, the election is OVER.) When you see comments like that, do you join the discussion or just observe?

June 18, 2009 | Unregistered CommenterRebecca

I guarantee that's from a "natural birth" Google alert!

I joined once. I will never join again. I felt terrible. I've been wanting to write about it-- maybe I will. I hope this post will catch a few searchers. I think every birth blogger should post some evidence about shoulder dystocia, since the info out there is either message boards or sleazy "should have estimated fetal weight and known to perform a c/s for that 9 pound baby" lawyer blogs.

June 18, 2009 | Registered CommenterJill

It's weird but I never thought I would be one to have SD at my birth. I knew docs (and MW's) were scared shitless about it-but never knew to the extent I know now. I don't think Hannah was considered macrosomic--she was 8 lbs. 14 oz at birth, and I am "petite". *eye roll*

If I do have #3, I would most likey go with another homebirth--but just for shits and giggles I should go to an OB and tell them I had a cesarean for FTP/CPD and a birth with SD, and want another VBAC. I might as well wear a shirt that reads:"WARNING: ticking time bomb of a lawsuit waiting to happen"

June 18, 2009 | Unregistered Commentermichele

Michele, did you read what "nowombpods" doctor told her after already having VBACed? "Your chances are 50/50 of having a VBAC." She was so pissed.

Hannah was at the cut off for macrosomia, btw. Kind of crazy that you WERE that one-ish percent. I often think about you and wonder how you're all doing.

I have an oddly high percentage of friends that have experienced SD (or an oddly high percentage of friends that talk about it?). It doesn't make it any less scary (especially to the midwife) but all were fine. One baby was temporarily injured for about six months and it went away-- arm is fine now.

June 18, 2009 | Registered CommenterJill

Speaking of Google, when you Google "shoulder dystocia" one out of every 4-5 links are to law firms. These sites target women with misinformation such as" you can predict should dystocia via ultrasound, and you should have had a C-section," as Jill alluded to. It makes me want to puke. This is the kind of money-grubbing crap that honest OB's, midwives and women are up against. It seems to me that the care of women has turned into a politicized, litigious, corrupt mess. I am hoping this tide is turning.

June 18, 2009 | Unregistered CommenterReality Rounds

Sometimes my "doula" alert kicks up blog posts like "I met with my doctor and she says she has to approve my doula" etc. I'm always torn about whether to post back, because of course I want to say "dump your doctor!" but at best I'd have to settle for "don't forget that this is your birth not your doctor's etc.". I'd be curious to hear about your experience.

June 22, 2009 | Unregistered CommenterRebecca
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