I'm in this process now nearly 34 weeks, got a scan tomorrow and another at 36 or 38 weeks to check for growth. My DD was 9lb 1oz and I'm 5ft with a tiny frame. She didn't even descend into my pelvis after 24 hours of induced labour so emcs. I don't think its the actual weight that is often the problem my DD had a 98th percentile head, my son to be is measuring 99th percentile head and stomach. I was told when my DD was born that her shoulders would have been too big to deliver naturally.
I've been told if expected to be over 4kg then I can have an elective. However, my hospital is very keen on vbacs and a decision on an elective is not normally made until 38 weeks.
If one more person tells me that you don't grow a baby that is too big for your pelvis...