I weigh by my own scale, naked in the morning, before breakfast, and my scale is digital. Add breakfast and clothing and I put o 3-5 lbs. Jump on the doc's digital scale and it's up 5-7 lbs. I know what I weighed before I got pregnant on my home scale and what I weigh now is right on track (21 lbs at 33 weeks), same gain on the doc's scale just 5-7 up from my home scale. I'm ok with that. It also seems to make a difference having had to go to the toilet. So you have to really do your own measures or else just go with whatever they say (which could be up to 7 lbs out in my books).