GD and Head Circumference ?

erstwhile+maven

With my first, it became apparent after he was born that I had undiagnosed GD.  I have GD this time as well, but controlling with diet. 

My DS was born at 37 weeks 1 day weighing 8lb 13oz.  He also had a 100th percentile head, something around 40 cm.  I pushed for hours then had to have a c-section b/c his head was too large for me.

I'm thinking for DD b/c my GD is controlled that I won't have the same problem with her head size but was wondering if anyone knows whether or not GD plays a role in bone growth... so many online resources indicate GD results in "fat" babies but I have to think growth overall is affected and that her head will likely be smaller.  Am I right or are DH's large head genes more to blame for this and I need to be prepared for another possible c-section for the same reason?

FWIW, my OB states that I'm a great candidate for a vbac.

Thanks for reading and for your insight!

ETA: Posting and running, thanks for your time.