they say your supposed to be 1cm for every week your pregnant but when i was at 38 weeks i was only measuring 32cm, i wouldnt worry to much im sure of the MW were concerned they would send you for a growth scan, i got one done as i thoughtth ebaby was huge and squashing all my insides to bits...lol turned out baby was fine and growing great when she was born she was only 6lbs 8 oz but that was huge to me...lol
take care xxxx