Mine came up at 4 lbs 3 oz at my 34 week scan last week. It looks just below the 10th percentile on the charts, so at a rate of about 1/2 pound per week until 40 weeks, yours should weigh around 6.5 pounds by then, so hardly a complete tiddler. It was a perfectly normal weight back in the 60s and 70s. Are you quite slight, and do you know your own birth weight?
That sort of movement sounds completely normal to me. They do need to stretch from time just as we do! Does he also get hiccoughs (rhythmic little jumps in roughly the same place for around 10-15 mins at a time)?
Thanks for your replies. Yes Duchesse, he does get hiccups quite frequent. I was very small before getting pregnant, size 6 not too sure of my own birth weight, think it was around 7lb. I've never thought of myself as having child bearing hips.