One OB at my practice has said to me TWICE, "If the baby is 10lbs we are not doing a VBAC." The first time I ignored her comment because she doesn't even deliver, but this last time I did ask, "Why does it increase your chances of a rupture?" She didn't really answer the question, but said something like, "Uhhh, the baby won't fit," and then went on to talk about about how we want to do what is best for the baby (of course, lady)! I chose not to get into it because, honestly, I haven't done a lot of reading on big babies and VBAC. I was under the impression that unless my pelvis was super narrow (it's not), it shouldn't matter, but maybe I'm wrong. Just wondering if anyone has experience with this or any great reading. Thanks for helping.
Re: Does anyone have any good resources about VBAC with a big baby?
My VBAC baby was 10 lb 10 oz, like chicsub said. My first son, who was a c-section, was 8 lb 4 oz. It was all in how they were lined up (my first was posterior, my second was anterior). I didn't have any sizing estimates (and in fact, turned down a routine NST u/s the day before I went into labor with DS2), and he was at least 41.5 weeks when he was born.
This is a good post about suspected macrosomia, and I think she has some links to studies at the end: https://birthsen.tmdhosting930.com/?p=1531
This post from the Unnecesarean doesn't talk directly about VBAC with big babies, but it does talk about the risks associated with c-sections and macrosomia (and might be worth it for some talking points? Read the comments, also!). https://www.theunnecesarean.com/blog/2011/11/20/how-i-would-counsel-a-woman-with-a-suspected-large-baby.html
Basically, when macrosomia is suspected, it's best not to do anything - active labor without an epidural is preferable, but not 100% necessary. Induction and c-sections aren't a cure-all, because the EDD could be off, and the baby could be too young, or the sizing estimates are off, and the c-section was unnecessary.
I personally would turn down any and all sizing u/s, and if u/s becomes necessary for some other reason, I'd request a size estimate not be taken. The main thing to remember about macrosomia is that it can only be truly diagnosed *after* the baby is born, so it's sorta pointless on all counts to speculate, you know?
Shoulder dystocia happens in about 1% of births, with the majority happening to babies who aren't macrosomic. The risk goes up to 5% with macrosomic babies, but again, you don't know if your baby is going to be macrosomic for certain, so it's not a huge risk.
Last thing: I had a midwife I saw occasionally when I was pregnant with DS2 who would tell me idiotic things about how I couldn't go past 41 weeks as a VBAC. When I asked her why not, she gave me the reason that VBAC was less successful with women past 41 weeks (probably because they get pushed into a RCS!). Anyhoo, her comments would drive me nuts, and I hated having appointments with her, but I did my best to ignore her. Providers can be idiots. Good luck!
DS2 - Oct 2010 (my VBAC baby!)
My first was over 10 lbs and my second was 8.5. For my VBAC my midwife said that a large baby might lower my chances but we would go for the VBAC regardless. I didn't have any growth ultrasounds.
That said, I know PLENTY of people who birthed babies over 10 lbs, so to just make a blanket statement that a baby that size wouldn't fit would make me lose respect for her as a doctor.