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Est Fetal Size / Previous Shoulder Dystocia

1069 Views 7 Replies 8 Participants Last post by  lifeguard
Following on from the 'Accuracy of US' thread, I would really appreciate some feed back here.

I hear and agree 100% with the consensus that US and other measuring techniques are not reliable especially after 20 weeks, and the general principle that women are able to give birth to the baby they make BUT does this still hold true if there has been a previous incidence of shoulder dystocia?

DS was 9lb 4oz, unexpectedly big (no scans, no measurements, no maternal weight gain checks in NZ) and a shoulder dystocia at birth requiring me to have an epis / Mcroberts / Woods Screw to get him out. I was flat on my back by this point after a long labour, and had previous tried pushing in various other positions to no avail. I appreciate that 'flipping' onto all fours might have worked but no way of knowing that now!

FFWd to today, and my babe is measuring big. The obs (here in France) is already murmuring about induction at term to avoid delivering a big baby - this was before he even heard about the previous SD. I want to hold out for another natural birth and - except for the previous SD - would be confident in doing so.

Any advice? Does a previous SD change the rules?
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I can only give my experience.

My 9 lb 15 oz baby had "sticky shoulders" (very mild dystocia). I delivered him on hands and knees and wasn't aware that this was even an issue til the first post-partum visit. So it wasn't bad. The next time I was pregnant, however, there was some concern about that, since the baby was obviously even bigger. But...10 lb 8 oz baby boy came barrelling out without any dystocia at all (I was also on hands and knees at the time).

So, who knows why the smaller baby's shoulders got stuck? But clearly it isn't all about size.
I have no personal experience with dystocia, but it seems to me that it's not an issue of size at all, but of positioning. I would not let the previous dystocia be anything but a reminder to keep yourself able to move to help a sticky baby. Good luck!
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Actually research shows that the risk of SD goes up - way up - as the baby gets over a certain size. So it is not an unfounded fear at all.

Of course, I don't know what can be done with that info!! With late-term US being really innaccurate for estimating fetal weight, there's really no way to know if induction at term could be useful in a specific case to avoid giving birth to a macrosomic baby.
Hopefully a MW could chime in here.
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I think it's a matter of size and position. My two biggest babies (just over and just under 9 lbs) had mild SD. The smaller one had a more severe case. In both cases, I was directed in my pushing. The first time was because I was a first time mom and didn't know better, and the second time was because of the mw's (unfounded) concerns. It's unlikely that my position had anything to do with it, as the first was delivered in a squat, the second on hands and knees.

I think that forced pushing doesn't allow the baby to get into a proper position and when the baby is bigger and heavier, that bone to bone impaction becomes a more serious problem. My other two babies were slightly smaller (by ounces) and neither had an issue because I pushed only when my body wanted to. I think that's one of the biggest keys.
Induction comes with its own set of risks, and as stated before, U/S is no kind of predictor of macrosomia. Plus, there's no way to tell if the correlation between macrosomic babies and SD is actually due to the macrosomia, KWIM? Mothers with GD may tend to have larger babies AND other issues (or forced interventions) that lead to malpositioning, and that could be clouding the data. There are all sorts of possibilities. But even if it's true that a malpositioned "big" baby is more likely to have trouble than a malpositioned average/small baby, the more significant factor seems to be positioning, not size.

If 90%+ of mothers are subject to conditions that can lead to poor positioning (lithotomy with epidural, AROM, early induction, etc.), then I wouldn't be surprised if the larger of their babies had an increased risk of associated issues (e.g.: SD). But in cases where women are allowed freedom of movement, evidence suggests that larger babies are less likely to be malpositioned, because they work better with gravity and with less space in the womb, have "nowhere to go."
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Without any scientific foundation to back myself up, I think position is huge. I had a SD with my second child (a UC birth) that resolved with a position change (thank G-d!). She was 9'10. My next child was over 10 1/2 lbs (another UC, this one a waterbirth). No SD, but he was way way better positioned. Then I had my fourth child (3rd UC) who was smaller, and no SD again. I'm expecting my fifth in Dec, and planning a midwife attended homebirth. I'm focusing on keeping fit and hoping to learn about more optimal fetal positioning.
Although a larger baby may be more likely to have a sd it's by no stretch a given.

As to the larger babies of mom's with gd - they are actually much more likely to have sd but it's not just because of the larger babies. Babies affected by gd are actually larger proportionally through the chest & shoulders - so it's a different kind of large & that's part of why they are more likely to have sd.
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