B (7:13)
All right, Anyway, so, yes, this is a big deal because we do fear the big fat baby in utero because of shoulder dystocia. Even though, if you read the guidance, most babies that get shoulder dystocia are not, you know, over the 4,000 macrosomic, even though they have a higher relative risk because most babies are not macrosomic, they're actually under that. And that's why shoulder dystocia is still relatively unpredictable, slash unpreventable, according to the guidance. Okay, now there's risk stratification, and we absolutely should do that. But as of right now, remember that neither ACOG nor SMFM does recommend early induction just because of the baby's weight. And that was covered in Practice Bulletin 178. Okay, that's the one on shoulder dystocia. Now, in that guidance, there's a very little, short, little paragraph. Well, it's not short, but a short section rather. On quote, is there any benefit to labor induction for the prevention of shoulder dystocia in the setting of suspected macrosomia or diabetes? End quote. That's the question raised. I'm reading that directly. I'm looking at it right now. 178. Is there any benefit to labor induction for the prevention of shoulder dystocia in the setting of suspected macrosomia or diabetes? End quote. Notice I highlighted and emphasized the word macrosomia. Now, this is a big deal here because whenever ACOG really talks about shoulder dystocia, even though it recognizes that not all babies with shoulder dystocia end up being macrosomic, they can be LGA. The guidance here is more clear on true macrosomia. 4000 grams or above. Okay, so keep that in mind, because a big baby trial wasn't really looking for macrosomia. It was including babies that were suspected of being lga. You understand that those are loosely associated but very different. So that all babies that are macrosomic are lga, but not all LGA babies are Macrosomic, Right? Because larger gestational age is greater than 90 percentile. Estimated fetal weight on ultrasound based on the week of gestation. So that you can have a 3.6 kilo baby be LGA at, you know, let's say, you know, 36 weeks. But not macrosomic. Because macrosomia is a set line. It's a boundary. It's a line in the sand of when you cross 4,000 grams, you're not macrosomic. All right? So keep that in mind. Right now, the college focuses more on macrosomia, whereas Big Baby said the Big Baby trial was more on LGA. Okay, now back to 178. And ACOG's answering this question. Is there any benefit to labor induction to prevent shoulder dystocia? Let me just read this directly, okay? Because the short answer is no. Quote, the American College of Obstetricians and Gynecologists recommends against delivery before 39 completed weeks of gestation, if not medically indicated. Whether induction is better than expected management for suspected lga. See, there it is. And at what gestational age delivery should be performed remains unclear. End quote. So let's stop there for a minute. So there they introduce the topic of lga. You're like, we don't know. We get macrosomia where we get the cutoffs of 5,000 grams without diabetes off resection, 4,500 grams with diabetes off resection. But we don't really know what's the best LGA determination and how many weeks to get out for shoulder dystia prevention. So that's where people get confused. Like, ah, well, the Big Baby trial looked at LGA and it answered that yes and no. Because the per protocol answer was one thing, the ITT answer was another. Remember, we're gonna get into short of it is the college continues. Although meta analyses of available trials is provocative and raises questions for further study, it is not clear that the reduction in shoulder dystocia found in the included trials would still persist if labor was induced after 39 weeks of gestation at this time. This is from the college. And until the results of additional studies are reported, the ACOG continues to discourage induction of labor and solely for suspected macrosomia at any gestational age, end quote. So that's the guidance as it stands now. Okay, now, yes, practice bulletin 178 is was originally done some years ago. However, it was. It's been re. Reaffirmed since that. So it's still valid. Okay, remember, that is the guidance on shoulder dystocia it was actually reaffirmed in 2024. Okay, reaffirmed 2024. Okay. So back to what we're talking about. So right now, college says, no, we need more data, especially with LGA because it gets very gray in the lancet. On May 17, 2025, the Big Baby trial was published. And that's what our podcast family member was asking about. The truth is, this was a big study. It had a big data source. It was good. Okay? It was very well done. And it looked at induction of labor for LGA babies, specifically looking at 38 to 38. Four for the reduction, shoulder dystocia versus expectant management. And sure enough, 40% reduction compared to standard care, which was delivery at or after 39 weeks in the per protocol. Per protocol. However, in the intent to treat analysis, there was no statistical significant difference. Okay, so let me. We're going to explain this here in a minute, by the way. Sorry, guys, I still have one nostril working. If you listen to the immediately passed episode, I'm working through my annual viral syndrome nos and much better now, but, you know, my respiration still come and go. Okay, anyway, so 40% sounds really good, especially when you consider that this had one of the largest, you know, patient recruitments to look at this, that used LGA as their. As a recruitment pool. Okay? So once again, let me give you what these actual numbers look like. So in the per protocol analysis, 40% reduction looks like this. 2.3% in the induction group for shoulder dystocia, 2.3 versus 3.7 in the standard care group. So again, 40% reduction is great, but, you know, 2.3 is definitely less than 3.7. Now take any reduction, but it's not. It's 40%. Again, good, but you have to understand what per protocol means. Per protocol means that even though the original two groups standard induction at 38 weeks, or standard induction or routine care at 39 weeks, even though they were randomized, some physicians and or patients left one group to go into the early induction because clinicians were afraid they broke protocol. Okay? And so they got. They left the intended design of the study called intent to treat, and then they bailed. So when you look at the per group, which includes those that were taken out of their randomized original trial and were added to this one, yes, it showed a reduction in shoulder association. That's great. However, the big catch here is that you lose the validity of the data of the randomization. The whole point of randomization is that you try to limit chance Right. And bias. So when you look at the PER protocol and go, wow, there was a reduction in shoulder dystocia. Great. However, it's not clear data, because that has the biggest issue here is selection bias. That, my friends, is the catch. The intent to treat analysis in itt. When most randomized trials have an ITT and a PER protocol, the ITT analysis preserves the benefits of randomization and it keeps the prognostic factor, in other words, the validity, accuracy of the data more pure. So in short, we should be more inclined to believe the scientific validity of intent to treat results. And in this one there was no statistical difference. Difference. Although PER protocol does mimic more real world, real world stuff in terms of statistics is muddied and confounded by selection bias. Okay, so all to say, intent to treat results are generally considered more reliable than per protocol results in randomized trials. And this is why in the big Baby study, the intent to treat pool found no difference. Which means what we probably saw as in that 40% reduction in shoulder dystocia 38 to 38 and four weeks was part of selection bias. Okay, now here's the other catch. Are you telling me that induction at 38 and four days gave a reduction in shoulder dystocia compared to 39 weeks in three days? I mean, we're talking about baby grazer grows about 30 grams a day, guys. That term, 30 grams a day. So you're telling me that the 90 grams difference prevented shoulder dosha? Doesn't make any sense. Even at 38 or 39 weeks, if we get out at 38, that additional week of baby's growth, baby grows half a pound a week. That's about 250 grams. Is 250 grams gonna be enough to push a baby over into shoulder dystocia? I don't know, it doesn't seem to be so. And that's what ACOG mentioned in that guidance. We're not sure at what EGA is valid. And even though meta analysis seemed to show this reduction, quote, it is unclear if the reduction in shoulder dystocia would have been still persistent if induction was found at 39 weeks. That's exactly what's in the guidance. In other words, we're not talking about a three week induction here earlier, guys, we're talking about a week. And in a week's growth, yes, baby is bigger a week later, assuming the placenta is functioning well. But the baby grows half a pound a week by grams, that's about, you know, 220, 250 grams this year. So 225 to 250 grams. Unclear if that's really going to move the needle all the way to shoulder dystocia. Guys. And I'm not minimizing the big baby trial, but the reason we didn't cover it initially is because, you know, when we first saw this come out in the Lancet, I told the team, they're like, well, do you want to do it? Is it confusing? I'm like, you know what, we already have clear guidance on this. We don't induce judge for that. We look for other reasons. I'm okay, I'm all for looking for other reasons to deliver. You suspect LGA look for other reasons to get out, but LGA by itself, really, as of right now, is not it. And this study actually verifies that per protocol. 40% reduction. Yes, I get that. But the intent to treat, which is pure data, did not actually show any significance, by the way. It's not just me. I'm not the only one saying this. There was actually a, a published commentary on this shortly after the, the published paper was released. And, and here's what we're going to give you with the three main, the three main limitations for this, we're going to call it a day. Okay? And again, I'll put the all of this in our show notes, but there's a very nice correspondence as a letter to the editor about this, which hit it exactly the nail on the head, which is what I'm trying to say here. First, limitation number one. The premature termination of the trial and crossover between the two study groups left little statistical power in the standard group compared to the induction group with a confidence interval that crossed one. So there it is right away. Confidence interval in this was 0.5 to 1.09. So while it was tight, the confidence interval crossed 1 and the P value was not significant in the intent to treat group. Okay, so they stopped the trial early. There was too many people leaving one group going into the early induction group, so the data is muddied. Number two, rather than using straight macrosomia, they use this looser eligibility, which we've already said of an estimated feet of weight above the ninth percentile, which is called, you know, lga, which actually doubled the estimated risk unnecessarily. In other words, if you just broaden the net to lga, it's gonna give you good capture. But most of your specificity in the data is with true macrosomia. And so this is why the actual birth weight mean in the control birth weight here was 3,857 grams, as opposed to a true macrosomia over 4,000 grams, which, again, you're not sure what to do with this. Even ACOG says not sure what to do with LGA versus true macrosomia number three, only 40%. Listen to this, guys. Only 40% of the participants deemed at high risk actually had the infant who was LGA at birth. In other words, when they weighed the child, like, hey, this kid's under 90th percentile, which means, quote, there was a 50% predictive value of late ultrasound for accuracy for fetal weight, end quote. This is what ACOG says. Ultrasound is good, it's just not great. And there's a lot of variance in there, up to 15, up to 20%. Room for error based on who you read. So in this study, 40% of those who were thought to be high risk for shoulder dystocia actually birthed an infant that was LGA, mirroring the 50% predictive value of late ultrasound. So all to say again, as ACOG says, this is why the bar is so high for offering a primary C section without diabetes of 5,000 grams, because ultrasound just has an inherent inaccuracy. And it's more inaccurate as gestation progresses, both for dating and for weight assessment. And that's why the values are for 5,000 grams without diabetes or 4.5 kilos, 4,500 grams with diabetes. Okay, now, before we leave the episode, I want to quote directly from this commentary again from the Lancet, published in October 2025. Remember, the original article came out in May of 2025, and then in October, actually, October 11, 2025, this commentary, which again, hit it right on the head, covers it beautifully. Let me just read you this last little statement here, this little paragraph, and we'll start wrapping this up. Quote, guideline committees, AKA smfm, nice guidelines, rcog, smfm, acog, whatever. Guideline committees should now consider whether to spend substantial resources. Uh. Oh, see, so it already starts off kind of negatively, Right? Guideline committee should now consider whether to spend substantial resources to recommend induction of labor in these patients. For. I'm reading it directly. Modest benefit. Okay? Not great benefit. Modest benefit given uncertain case findings, period. So right in the first sentence is like, hey, we're unsure. Committees are got to be really sure if they're going to change guidance based on this because, quote, it has uncertain case findings, then, quote, they go on, quote, until better tools become available, nuanced counseling is the most promising strategy. Women with a fetus above the 90th percentile might await labor, whereas those with a fetus above the 95th percentile or greater or a birth weight above 4,500 grams or a previous shoulder dystocia or rising morbidity might choose induction or elective cesarean. So in this last paragraph it says, hey, just pump the brakes here. We need better data, we need less crossover, we need trials to not finish early. Because it's unclear these uncertain case findings before we change, guidance here may be a way to cleaner data. Okay, that's all they're saying. So my take home message as we get ready to wrap this up again, look for a reason if you're really worried about it, under 39 weeks that you can medically be cleared to get out. And patient history is one thing. The second issue has to do with 39 weeks. If you suspect baby is LGA, but below the cutoffs for offering a primary section, why would you go past 39 weeks at 39 weeks with good dating, you don't even need a reason. That's elective induction. Assuming the cervix is favorable and the patient accepts risks. All to say induction early just for suspected fetal weight is more complicated than the 40% reduction found in the per protocol analysis from a study that found no statistical difference in shoulder dystocia in the intent to treat. So I think I've said that enough. Let's get ready to start wrapping this up. But anyway, that was the correspondence from October 11, 2025 in the same journal the lance it so to our podcast family member that asked about the big baby trial. Yes, it was very significant. However, there was a lot of crossover, the end of the trial early, their selection bias and so here's my take home message. I look for things at 38 weeks if I think this kid is ginormous yet under let me just back phrase that, backpedal that a little bit under the cutoffs but I am worried. Then I look for other things. Is she dilated early? She in latent phase? Is her blood pressure issues, anything else that can give us a medical justification to get out now, all with the patient's history. Guys, if she's had three previous shoulder dystocias, why has she had three? That's the first question. I'm just making this for point of emphasis because the biggest history of shoulder dystocia. The biggest history, the biggest risk for shoulder dystocia, while big baby is one. It's a previous history of shoulder dystocia that complicates matters.
