I've used one for the last 6 years....and when I know they are close by showing me the signs they usually do...squatting, sitting, being peg legged as well as loose ligs and discharge, I tend to go to bed with the moniter on my pillow...A change in breathing...grunty like usually gets me up to the barn...and back again once I see that she's going to be awhile...a good holler gets me running to the barn at breakneck speed.