I am currently 32 wks + 6 days pg with a small for age baby.
as of monday (32wks +3days) she weighs 1.4kg and has only gained 255g in 2 weeks (since 30 wks +3days).
At the moment I am visiting the hospital twice a week for CTG scans and once a week for Ultrasounds. They've run a million and one blood tests etc and can't find anything causing her to be small. So I guess I'm just having a small baby.
My theory is as long as you're comfortable that the Dr's/Midwives are keeping an eye on you and bub and every test they do comes back normal, then you can breath a little easier.