does anyone know anything about them? specifically the uterine activity bit. im just curious as i have been on one for hours (just got home now) and the number was at times going from 19 to 31 ranging that, when normally when ive had it done before it just stayed at 20 or whatever or only went up or down 1 point. and one time when it did it i got a weird feeling in my tummy, like baby was moving but weirder like a pressure that was uncomfy. just wondered! x